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diff --git a/Documentation/gpu/afbc.rst b/Documentation/gpu/afbc.rst new file mode 100644 index 000000000..4d38dc49d --- /dev/null +++ b/Documentation/gpu/afbc.rst @@ -0,0 +1,235 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +=================================== + Arm Framebuffer Compression (AFBC) +=================================== + +AFBC is a proprietary lossless image compression protocol and format. +It provides fine-grained random access and minimizes the amount of +data transferred between IP blocks. + +AFBC can be enabled on drivers which support it via use of the AFBC +format modifiers defined in drm_fourcc.h. See DRM_FORMAT_MOD_ARM_AFBC(*). + +All users of the AFBC modifiers must follow the usage guidelines laid +out in this document, to ensure compatibility across different AFBC +producers and consumers. + +Components and Ordering +======================= + +AFBC streams can contain several components - where a component +corresponds to a color channel (i.e. R, G, B, X, A, Y, Cb, Cr). +The assignment of input/output color channels must be consistent +between the encoder and the decoder for correct operation, otherwise +the consumer will interpret the decoded data incorrectly. + +Furthermore, when the lossless colorspace transform is used +(AFBC_FORMAT_MOD_YTR, which should be enabled for RGB buffers for +maximum compression efficiency), the component order must be: + + * Component 0: R + * Component 1: G + * Component 2: B + +The component ordering is communicated via the fourcc code in the +fourcc:modifier pair. In general, component '0' is considered to +reside in the least-significant bits of the corresponding linear +format. For example, COMP(bits): + + * DRM_FORMAT_ABGR8888 + + * Component 0: R(8) + * Component 1: G(8) + * Component 2: B(8) + * Component 3: A(8) + + * DRM_FORMAT_BGR888 + + * Component 0: R(8) + * Component 1: G(8) + * Component 2: B(8) + + * DRM_FORMAT_YUYV + + * Component 0: Y(8) + * Component 1: Cb(8, 2x1 subsampled) + * Component 2: Cr(8, 2x1 subsampled) + +In AFBC, 'X' components are not treated any differently from any other +component. Therefore, an AFBC buffer with fourcc DRM_FORMAT_XBGR8888 +encodes with 4 components, like so: + + * DRM_FORMAT_XBGR8888 + + * Component 0: R(8) + * Component 1: G(8) + * Component 2: B(8) + * Component 3: X(8) + +Please note, however, that the inclusion of a "wasted" 'X' channel is +bad for compression efficiency, and so it's recommended to avoid +formats containing 'X' bits. If a fourth component is +required/expected by the encoder/decoder, then it is recommended to +instead use an equivalent format with alpha, setting all alpha bits to +'1'. If there is no requirement for a fourth component, then a format +which doesn't include alpha can be used, e.g. DRM_FORMAT_BGR888. + +Number of Planes +================ + +Formats which are typically multi-planar in linear layouts (e.g. YUV +420), can be encoded into one, or multiple, AFBC planes. As with +component order, the encoder and decoder must agree about the number +of planes in order to correctly decode the buffer. The fourcc code is +used to determine the number of encoded planes in an AFBC buffer, +matching the number of planes for the linear (unmodified) format. +Within each plane, the component ordering also follows the fourcc +code: + +For example: + + * DRM_FORMAT_YUYV: nplanes = 1 + + * Plane 0: + + * Component 0: Y(8) + * Component 1: Cb(8, 2x1 subsampled) + * Component 2: Cr(8, 2x1 subsampled) + + * DRM_FORMAT_NV12: nplanes = 2 + + * Plane 0: + + * Component 0: Y(8) + + * Plane 1: + + * Component 0: Cb(8, 2x1 subsampled) + * Component 1: Cr(8, 2x1 subsampled) + +Cross-device interoperability +============================= + +For maximum compatibility across devices, the table below defines +canonical formats for use between AFBC-enabled devices. Formats which +are listed here must be used exactly as specified when using the AFBC +modifiers. Formats which are not listed should be avoided. + +.. flat-table:: AFBC formats + + * - Fourcc code + - Description + - Planes/Components + + * - DRM_FORMAT_ABGR2101010 + - 10-bit per component RGB, with 2-bit alpha + - Plane 0: 4 components + * Component 0: R(10) + * Component 1: G(10) + * Component 2: B(10) + * Component 3: A(2) + + * - DRM_FORMAT_ABGR8888 + - 8-bit per component RGB, with 8-bit alpha + - Plane 0: 4 components + * Component 0: R(8) + * Component 1: G(8) + * Component 2: B(8) + * Component 3: A(8) + + * - DRM_FORMAT_BGR888 + - 8-bit per component RGB + - Plane 0: 3 components + * Component 0: R(8) + * Component 1: G(8) + * Component 2: B(8) + + * - DRM_FORMAT_BGR565 + - 5/6-bit per component RGB + - Plane 0: 3 components + * Component 0: R(5) + * Component 1: G(6) + * Component 2: B(5) + + * - DRM_FORMAT_ABGR1555 + - 5-bit per component RGB, with 1-bit alpha + - Plane 0: 4 components + * Component 0: R(5) + * Component 1: G(5) + * Component 2: B(5) + * Component 3: A(1) + + * - DRM_FORMAT_VUY888 + - 8-bit per component YCbCr 444, single plane + - Plane 0: 3 components + * Component 0: Y(8) + * Component 1: Cb(8) + * Component 2: Cr(8) + + * - DRM_FORMAT_VUY101010 + - 10-bit per component YCbCr 444, single plane + - Plane 0: 3 components + * Component 0: Y(10) + * Component 1: Cb(10) + * Component 2: Cr(10) + + * - DRM_FORMAT_YUYV + - 8-bit per component YCbCr 422, single plane + - Plane 0: 3 components + * Component 0: Y(8) + * Component 1: Cb(8, 2x1 subsampled) + * Component 2: Cr(8, 2x1 subsampled) + + * - DRM_FORMAT_NV16 + - 8-bit per component YCbCr 422, two plane + - Plane 0: 1 component + * Component 0: Y(8) + Plane 1: 2 components + * Component 0: Cb(8, 2x1 subsampled) + * Component 1: Cr(8, 2x1 subsampled) + + * - DRM_FORMAT_Y210 + - 10-bit per component YCbCr 422, single plane + - Plane 0: 3 components + * Component 0: Y(10) + * Component 1: Cb(10, 2x1 subsampled) + * Component 2: Cr(10, 2x1 subsampled) + + * - DRM_FORMAT_P210 + - 10-bit per component YCbCr 422, two plane + - Plane 0: 1 component + * Component 0: Y(10) + Plane 1: 2 components + * Component 0: Cb(10, 2x1 subsampled) + * Component 1: Cr(10, 2x1 subsampled) + + * - DRM_FORMAT_YUV420_8BIT + - 8-bit per component YCbCr 420, single plane + - Plane 0: 3 components + * Component 0: Y(8) + * Component 1: Cb(8, 2x2 subsampled) + * Component 2: Cr(8, 2x2 subsampled) + + * - DRM_FORMAT_YUV420_10BIT + - 10-bit per component YCbCr 420, single plane + - Plane 0: 3 components + * Component 0: Y(10) + * Component 1: Cb(10, 2x2 subsampled) + * Component 2: Cr(10, 2x2 subsampled) + + * - DRM_FORMAT_NV12 + - 8-bit per component YCbCr 420, two plane + - Plane 0: 1 component + * Component 0: Y(8) + Plane 1: 2 components + * Component 0: Cb(8, 2x2 subsampled) + * Component 1: Cr(8, 2x2 subsampled) + + * - DRM_FORMAT_P010 + - 10-bit per component YCbCr 420, two plane + - Plane 0: 1 component + * Component 0: Y(10) + Plane 1: 2 components + * Component 0: Cb(10, 2x2 subsampled) + * Component 1: Cr(10, 2x2 subsampled) diff --git a/Documentation/gpu/amdgpu-dc.rst b/Documentation/gpu/amdgpu-dc.rst new file mode 100644 index 000000000..cc89b0fc1 --- /dev/null +++ b/Documentation/gpu/amdgpu-dc.rst @@ -0,0 +1,68 @@ +=================================== +drm/amd/display - Display Core (DC) +=================================== + +*placeholder - general description of supported platforms, what dc is, etc.* + +Because it is partially shared with other operating systems, the Display Core +Driver is divided in two pieces. + +1. **Display Core (DC)** contains the OS-agnostic components. Things like + hardware programming and resource management are handled here. +2. **Display Manager (DM)** contains the OS-dependent components. Hooks to the + amdgpu base driver and DRM are implemented here. + +It doesn't help that the entire package is frequently referred to as DC. But +with the context in mind, it should be clear. + +When CONFIG_DRM_AMD_DC is enabled, DC will be initialized by default for +supported ASICs. To force disable, set `amdgpu.dc=0` on kernel command line. +Likewise, to force enable on unsupported ASICs, set `amdgpu.dc=1`. + +To determine if DC is loaded, search dmesg for the following entry: + +``Display Core initialized with <version number here>`` + +AMDgpu Display Manager +====================== + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h + :internal: + +Lifecycle +--------- + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c + :doc: DM Lifecycle + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c + :functions: dm_hw_init dm_hw_fini + +Interrupts +---------- + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_irq.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c + :functions: register_hpd_handlers dm_crtc_high_irq dm_pflip_high_irq + +Atomic Implementation +--------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c + :doc: atomic + +.. kernel-doc:: drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c + :functions: amdgpu_dm_atomic_check amdgpu_dm_atomic_commit_tail + +Display Core +============ + +**WIP** diff --git a/Documentation/gpu/amdgpu.rst b/Documentation/gpu/amdgpu.rst new file mode 100644 index 000000000..2062a6023 --- /dev/null +++ b/Documentation/gpu/amdgpu.rst @@ -0,0 +1,303 @@ +========================= + drm/amdgpu AMDgpu driver +========================= + +The drm/amdgpu driver supports all AMD Radeon GPUs based on the Graphics Core +Next (GCN) architecture. + +Module Parameters +================= + +The amdgpu driver supports the following module parameters: + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c + +Core Driver Infrastructure +========================== + +This section covers core driver infrastructure. + +.. _amdgpu_memory_domains: + +Memory Domains +-------------- + +.. kernel-doc:: include/uapi/drm/amdgpu_drm.h + :doc: memory domains + +Buffer Objects +-------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_object.c + :doc: amdgpu_object + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_object.c + :internal: + +PRIME Buffer Sharing +-------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c + :doc: PRIME Buffer Sharing + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c + :internal: + +MMU Notifier +------------ + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c + :doc: MMU Notifier + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c + :internal: + +AMDGPU Virtual Memory +--------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c + :doc: GPUVM + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c + :internal: + +Interrupt Handling +------------------ + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c + :doc: Interrupt Handling + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_irq.c + :internal: + +IP Blocks +------------------ + +.. kernel-doc:: drivers/gpu/drm/amd/include/amd_shared.h + :doc: IP Blocks + +.. kernel-doc:: drivers/gpu/drm/amd/include/amd_shared.h + :identifiers: amd_ip_block_type amd_ip_funcs + +AMDGPU XGMI Support +=================== + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c + +AMDGPU RAS Support +================== + +The AMDGPU RAS interfaces are exposed via sysfs (for informational queries) and +debugfs (for error injection). + +RAS debugfs/sysfs Control and Error Injection Interfaces +-------------------------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c + :doc: AMDGPU RAS debugfs control interface + +RAS Reboot Behavior for Unrecoverable Errors +-------------------------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c + :doc: AMDGPU RAS Reboot Behavior for Unrecoverable Errors + +RAS Error Count sysfs Interface +------------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c + :doc: AMDGPU RAS sysfs Error Count Interface + +RAS EEPROM debugfs Interface +---------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c + :doc: AMDGPU RAS debugfs EEPROM table reset interface + +RAS VRAM Bad Pages sysfs Interface +---------------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c + :doc: AMDGPU RAS sysfs gpu_vram_bad_pages Interface + +Sample Code +----------- +Sample code for testing error injection can be found here: +https://cgit.freedesktop.org/mesa/drm/tree/tests/amdgpu/ras_tests.c + +This is part of the libdrm amdgpu unit tests which cover several areas of the GPU. +There are four sets of tests: + +RAS Basic Test + +The test verifies the RAS feature enabled status and makes sure the necessary sysfs and debugfs files +are present. + +RAS Query Test + +This test checks the RAS availability and enablement status for each supported IP block as well as +the error counts. + +RAS Inject Test + +This test injects errors for each IP. + +RAS Disable Test + +This test tests disabling of RAS features for each IP block. + + +GPU Power/Thermal Controls and Monitoring +========================================= + +This section covers hwmon and power/thermal controls. + +HWMON Interfaces +---------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: hwmon + +GPU sysfs Power State Interfaces +-------------------------------- + +GPU power controls are exposed via sysfs files. + +power_dpm_state +~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: power_dpm_state + +power_dpm_force_performance_level +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: power_dpm_force_performance_level + +pp_table +~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pp_table + +pp_od_clk_voltage +~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pp_od_clk_voltage + +pp_dpm_* +~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pp_dpm_sclk pp_dpm_mclk pp_dpm_socclk pp_dpm_fclk pp_dpm_dcefclk pp_dpm_pcie + +pp_power_profile_mode +~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pp_power_profile_mode + +\*_busy_percent +~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: gpu_busy_percent + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: mem_busy_percent + +gpu_metrics +~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: gpu_metrics + +GPU Product Information +======================= + +Information about the GPU can be obtained on certain cards +via sysfs + +product_name +------------ + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c + :doc: product_name + +product_number +-------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c + :doc: product_name + +serial_number +------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c + :doc: serial_number + +unique_id +--------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: unique_id + +GPU Memory Usage Information +============================ + +Various memory accounting can be accessed via sysfs + +mem_info_vram_total +------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c + :doc: mem_info_vram_total + +mem_info_vram_used +------------------ + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c + :doc: mem_info_vram_used + +mem_info_vis_vram_total +----------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c + :doc: mem_info_vis_vram_total + +mem_info_vis_vram_used +---------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c + :doc: mem_info_vis_vram_used + +mem_info_gtt_total +------------------ + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c + :doc: mem_info_gtt_total + +mem_info_gtt_used +----------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c + :doc: mem_info_gtt_used + +PCIe Accounting Information +=========================== + +pcie_bw +------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pcie_bw + +pcie_replay_count +----------------- + +.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c + :doc: pcie_replay_count + + diff --git a/Documentation/gpu/backlight.rst b/Documentation/gpu/backlight.rst new file mode 100644 index 000000000..9ebfc9d0a --- /dev/null +++ b/Documentation/gpu/backlight.rst @@ -0,0 +1,12 @@ +================= +Backlight support +================= + +.. kernel-doc:: drivers/video/backlight/backlight.c + :doc: overview + +.. kernel-doc:: include/linux/backlight.h + :internal: + +.. kernel-doc:: drivers/video/backlight/backlight.c + :export: diff --git a/Documentation/gpu/bridge/dw-hdmi.rst b/Documentation/gpu/bridge/dw-hdmi.rst new file mode 100644 index 000000000..486faadf0 --- /dev/null +++ b/Documentation/gpu/bridge/dw-hdmi.rst @@ -0,0 +1,15 @@ +======================================================= + drm/bridge/dw-hdmi Synopsys DesignWare HDMI Controller +======================================================= + +Synopsys DesignWare HDMI Controller +=================================== + +This section covers everything related to the Synopsys DesignWare HDMI +Controller implemented as a DRM bridge. + +Supported Input Formats and Encodings +------------------------------------- + +.. kernel-doc:: include/drm/bridge/dw_hdmi.h + :doc: Supported input formats and encodings diff --git a/Documentation/gpu/dp-mst/topology-figure-1.dot b/Documentation/gpu/dp-mst/topology-figure-1.dot new file mode 100644 index 000000000..157e17c7e --- /dev/null +++ b/Documentation/gpu/dp-mst/topology-figure-1.dot @@ -0,0 +1,52 @@ +digraph T { + /* Make sure our payloads are always drawn below the driver node */ + subgraph cluster_driver { + fillcolor = grey; + style = filled; + driver -> {payload1, payload2} [dir=none]; + } + + /* Driver malloc references */ + edge [style=dashed]; + driver -> port1; + driver -> port2; + driver -> port3:e; + driver -> port4; + + payload1:s -> port1:e; + payload2:s -> port3:e; + edge [style=""]; + + subgraph cluster_topology { + label="Topology Manager"; + labelloc=bottom; + + /* Topology references */ + mstb1 -> {port1, port2}; + port1 -> mstb2; + port2 -> mstb3 -> {port3, port4}; + port3 -> mstb4; + + /* Malloc references */ + edge [style=dashed;dir=back]; + mstb1 -> {port1, port2}; + port1 -> mstb2; + port2 -> mstb3 -> {port3, port4}; + port3 -> mstb4; + } + + driver [label="DRM driver";style=filled;shape=box;fillcolor=lightblue]; + + payload1 [label="Payload #1";style=filled;shape=box;fillcolor=lightblue]; + payload2 [label="Payload #2";style=filled;shape=box;fillcolor=lightblue]; + + mstb1 [label="MSTB #1";style=filled;fillcolor=palegreen;shape=oval]; + mstb2 [label="MSTB #2";style=filled;fillcolor=palegreen;shape=oval]; + mstb3 [label="MSTB #3";style=filled;fillcolor=palegreen;shape=oval]; + mstb4 [label="MSTB #4";style=filled;fillcolor=palegreen;shape=oval]; + + port1 [label="Port #1";shape=oval]; + port2 [label="Port #2";shape=oval]; + port3 [label="Port #3";shape=oval]; + port4 [label="Port #4";shape=oval]; +} diff --git a/Documentation/gpu/dp-mst/topology-figure-2.dot b/Documentation/gpu/dp-mst/topology-figure-2.dot new file mode 100644 index 000000000..4243dd173 --- /dev/null +++ b/Documentation/gpu/dp-mst/topology-figure-2.dot @@ -0,0 +1,56 @@ +digraph T { + /* Make sure our payloads are always drawn below the driver node */ + subgraph cluster_driver { + fillcolor = grey; + style = filled; + driver -> {payload1, payload2} [dir=none]; + } + + /* Driver malloc references */ + edge [style=dashed]; + driver -> port1; + driver -> port2; + driver -> port3:e; + driver -> port4 [color=red]; + + payload1:s -> port1:e; + payload2:s -> port3:e; + edge [style=""]; + + subgraph cluster_topology { + label="Topology Manager"; + labelloc=bottom; + + /* Topology references */ + mstb1 -> {port1, port2}; + port1 -> mstb2; + edge [color=red]; + port2 -> mstb3 -> {port3, port4}; + port3 -> mstb4; + edge [color=""]; + + /* Malloc references */ + edge [style=dashed;dir=back]; + mstb1 -> {port1, port2}; + port1 -> mstb2; + port2 -> mstb3 -> port3; + edge [color=red]; + mstb3 -> port4; + port3 -> mstb4; + } + + mstb1 [label="MSTB #1";style=filled;fillcolor=palegreen]; + mstb2 [label="MSTB #2";style=filled;fillcolor=palegreen]; + mstb3 [label="MSTB #3";style=filled;fillcolor=palegreen]; + mstb4 [label="MSTB #4";style=filled;fillcolor=grey]; + + port1 [label="Port #1"]; + port2 [label="Port #2"]; + port3 [label="Port #3"]; + port4 [label="Port #4";style=filled;fillcolor=grey]; + + driver [label="DRM driver";style=filled;shape=box;fillcolor=lightblue]; + + payload1 [label="Payload #1";style=filled;shape=box;fillcolor=lightblue]; + payload2 [label="Payload #2";style=filled;shape=box;fillcolor=lightblue]; +} diff --git a/Documentation/gpu/dp-mst/topology-figure-3.dot b/Documentation/gpu/dp-mst/topology-figure-3.dot new file mode 100644 index 000000000..6cd78d067 --- /dev/null +++ b/Documentation/gpu/dp-mst/topology-figure-3.dot @@ -0,0 +1,59 @@ +digraph T { + /* Make sure our payloads are always drawn below the driver node */ + subgraph cluster_driver { + fillcolor = grey; + style = filled; + edge [dir=none]; + driver -> payload1; + driver -> payload2 [penwidth=3]; + edge [dir=""]; + } + + /* Driver malloc references */ + edge [style=dashed]; + driver -> port1; + driver -> port2; + driver -> port3:e; + driver -> port4 [color=grey]; + payload1:s -> port1:e; + payload2:s -> port3:e [penwidth=3]; + edge [style=""]; + + subgraph cluster_topology { + label="Topology Manager"; + labelloc=bottom; + + /* Topology references */ + mstb1 -> {port1, port2}; + port1 -> mstb2; + edge [color=grey]; + port2 -> mstb3 -> {port3, port4}; + port3 -> mstb4; + edge [color=""]; + + /* Malloc references */ + edge [style=dashed;dir=back]; + mstb1 -> {port1, port2}; + port1 -> mstb2; + port2 -> mstb3 [penwidth=3]; + mstb3 -> port3 [penwidth=3]; + edge [color=grey]; + mstb3 -> port4; + port3 -> mstb4; + } + + mstb1 [label="MSTB #1";style=filled;fillcolor=palegreen]; + mstb2 [label="MSTB #2";style=filled;fillcolor=palegreen]; + mstb3 [label="MSTB #3";style=filled;fillcolor=palegreen;penwidth=3]; + mstb4 [label="MSTB #4";style=filled;fillcolor=grey]; + + port1 [label="Port #1"]; + port2 [label="Port #2";penwidth=5]; + port3 [label="Port #3";penwidth=3]; + port4 [label="Port #4";style=filled;fillcolor=grey]; + + driver [label="DRM driver";style=filled;shape=box;fillcolor=lightblue]; + + payload1 [label="Payload #1";style=filled;shape=box;fillcolor=lightblue]; + payload2 [label="Payload #2";style=filled;shape=box;fillcolor=lightblue;penwidth=3]; +} diff --git a/Documentation/gpu/drivers.rst b/Documentation/gpu/drivers.rst new file mode 100644 index 000000000..b4a0ed3ca --- /dev/null +++ b/Documentation/gpu/drivers.rst @@ -0,0 +1,28 @@ +======================== +GPU Driver Documentation +======================== + +.. toctree:: + + amdgpu + amdgpu-dc + i915 + mcde + meson + pl111 + tegra + tve200 + v3d + vc4 + vkms + bridge/dw-hdmi + xen-front + afbc + komeda-kms + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/gpu/drm-client.rst b/Documentation/gpu/drm-client.rst new file mode 100644 index 000000000..58b5a1d12 --- /dev/null +++ b/Documentation/gpu/drm-client.rst @@ -0,0 +1,15 @@ +================= +Kernel clients +================= + +.. kernel-doc:: drivers/gpu/drm/drm_client.c + :doc: overview + +.. kernel-doc:: include/drm/drm_client.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_client.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_client_modeset.c + :export: diff --git a/Documentation/gpu/drm-internals.rst b/Documentation/gpu/drm-internals.rst new file mode 100644 index 000000000..12272b168 --- /dev/null +++ b/Documentation/gpu/drm-internals.rst @@ -0,0 +1,232 @@ +============= +DRM Internals +============= + +This chapter documents DRM internals relevant to driver authors and +developers working to add support for the latest features to existing +drivers. + +First, we go over some typical driver initialization requirements, like +setting up command buffers, creating an initial output configuration, +and initializing core services. Subsequent sections cover core internals +in more detail, providing implementation notes and examples. + +The DRM layer provides several services to graphics drivers, many of +them driven by the application interfaces it provides through libdrm, +the library that wraps most of the DRM ioctls. These include vblank +event handling, memory management, output management, framebuffer +management, command submission & fencing, suspend/resume support, and +DMA services. + +Driver Initialization +===================== + +At the core of every DRM driver is a :c:type:`struct drm_driver +<drm_driver>` structure. Drivers typically statically initialize +a drm_driver structure, and then pass it to +drm_dev_alloc() to allocate a device instance. After the +device instance is fully initialized it can be registered (which makes +it accessible from userspace) using drm_dev_register(). + +The :c:type:`struct drm_driver <drm_driver>` structure +contains static information that describes the driver and features it +supports, and pointers to methods that the DRM core will call to +implement the DRM API. We will first go through the :c:type:`struct +drm_driver <drm_driver>` static information fields, and will +then describe individual operations in details as they get used in later +sections. + +Driver Information +------------------ + +Major, Minor and Patchlevel +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +int major; int minor; int patchlevel; +The DRM core identifies driver versions by a major, minor and patch +level triplet. The information is printed to the kernel log at +initialization time and passed to userspace through the +DRM_IOCTL_VERSION ioctl. + +The major and minor numbers are also used to verify the requested driver +API version passed to DRM_IOCTL_SET_VERSION. When the driver API +changes between minor versions, applications can call +DRM_IOCTL_SET_VERSION to select a specific version of the API. If the +requested major isn't equal to the driver major, or the requested minor +is larger than the driver minor, the DRM_IOCTL_SET_VERSION call will +return an error. Otherwise the driver's set_version() method will be +called with the requested version. + +Name, Description and Date +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +char \*name; char \*desc; char \*date; +The driver name is printed to the kernel log at initialization time, +used for IRQ registration and passed to userspace through +DRM_IOCTL_VERSION. + +The driver description is a purely informative string passed to +userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by +the kernel. + +The driver date, formatted as YYYYMMDD, is meant to identify the date of +the latest modification to the driver. However, as most drivers fail to +update it, its value is mostly useless. The DRM core prints it to the +kernel log at initialization time and passes it to userspace through the +DRM_IOCTL_VERSION ioctl. + +Device Instance and Driver Handling +----------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_drv.c + :doc: driver instance overview + +.. kernel-doc:: include/drm/drm_device.h + :internal: + +.. kernel-doc:: include/drm/drm_drv.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_drv.c + :export: + +Driver Load +----------- + +Component Helper Usage +~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/drm_drv.c + :doc: component helper usage recommendations + +IRQ Helper Library +~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/drm_irq.c + :doc: irq helpers + +.. kernel-doc:: drivers/gpu/drm/drm_irq.c + :export: + +Memory Manager Initialization +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Every DRM driver requires a memory manager which must be initialized at +load time. DRM currently contains two memory managers, the Translation +Table Manager (TTM) and the Graphics Execution Manager (GEM). This +document describes the use of the GEM memory manager only. See ? for +details. + +Miscellaneous Device Configuration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Another task that may be necessary for PCI devices during configuration +is mapping the video BIOS. On many devices, the VBIOS describes device +configuration, LCD panel timings (if any), and contains flags indicating +device state. Mapping the BIOS can be done using the pci_map_rom() +call, a convenience function that takes care of mapping the actual ROM, +whether it has been shadowed into memory (typically at address 0xc0000) +or exists on the PCI device in the ROM BAR. Note that after the ROM has +been mapped and any necessary information has been extracted, it should +be unmapped; on many devices, the ROM address decoder is shared with +other BARs, so leaving it mapped could cause undesired behaviour like +hangs or memory corruption. + +Managed Resources +----------------- + +.. kernel-doc:: drivers/gpu/drm/drm_managed.c + :doc: managed resources + +.. kernel-doc:: drivers/gpu/drm/drm_managed.c + :export: + +.. kernel-doc:: include/drm/drm_managed.h + :internal: + +Bus-specific Device Registration and PCI Support +------------------------------------------------ + +A number of functions are provided to help with device registration. The +functions deal with PCI and platform devices respectively and are only +provided for historical reasons. These are all deprecated and shouldn't +be used in new drivers. Besides that there's a few helpers for pci +drivers. + +.. kernel-doc:: drivers/gpu/drm/drm_pci.c + :export: + +Open/Close, File Operations and IOCTLs +====================================== + +.. _drm_driver_fops: + +File Operations +--------------- + +.. kernel-doc:: drivers/gpu/drm/drm_file.c + :doc: file operations + +.. kernel-doc:: include/drm/drm_file.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_file.c + :export: + +Misc Utilities +============== + +Printer +------- + +.. kernel-doc:: include/drm/drm_print.h + :doc: print + +.. kernel-doc:: include/drm/drm_print.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_print.c + :export: + +Utilities +--------- + +.. kernel-doc:: include/drm/drm_util.h + :doc: drm utils + +.. kernel-doc:: include/drm/drm_util.h + :internal: + + +Legacy Support Code +=================== + +The section very briefly covers some of the old legacy support code +which is only used by old DRM drivers which have done a so-called +shadow-attach to the underlying device instead of registering as a real +driver. This also includes some of the old generic buffer management and +command submission code. Do not use any of this in new and modern +drivers. + +Legacy Suspend/Resume +--------------------- + +The DRM core provides some suspend/resume code, but drivers wanting full +suspend/resume support should provide save() and restore() functions. +These are called at suspend, hibernate, or resume time, and should +perform any state save or restore required by your device across suspend +or hibernate states. + +int (\*suspend) (struct drm_device \*, pm_message_t state); int +(\*resume) (struct drm_device \*); +Those are legacy suspend and resume methods which *only* work with the +legacy shadow-attach driver registration functions. New driver should +use the power management interface provided by their bus type (usually +through the :c:type:`struct device_driver <device_driver>` +dev_pm_ops) and set these methods to NULL. + +Legacy DMA Services +------------------- + +This should cover how DMA mapping etc. is supported by the core. These +functions are deprecated and should not be used. diff --git a/Documentation/gpu/drm-kms-helpers.rst b/Documentation/gpu/drm-kms-helpers.rst new file mode 100644 index 000000000..b89ddd06d --- /dev/null +++ b/Documentation/gpu/drm-kms-helpers.rst @@ -0,0 +1,413 @@ +============================= +Mode Setting Helper Functions +============================= + +The DRM subsystem aims for a strong separation between core code and helper +libraries. Core code takes care of general setup and teardown and decoding +userspace requests to kernel internal objects. Everything else is handled by a +large set of helper libraries, which can be combined freely to pick and choose +for each driver what fits, and avoid shared code where special behaviour is +needed. + +This distinction between core code and helpers is especially strong in the +modesetting code, where there's a shared userspace ABI for all drivers. This is +in contrast to the render side, where pretty much everything (with very few +exceptions) can be considered optional helper code. + +There are a few areas these helpers can grouped into: + +* Helpers to implement modesetting. The important ones here are the atomic + helpers. Old drivers still often use the legacy CRTC helpers. They both share + the same set of common helper vtables. For really simple drivers (anything + that would have been a great fit in the deprecated fbdev subsystem) there's + also the simple display pipe helpers. + +* There's a big pile of helpers for handling outputs. First the generic bridge + helpers for handling encoder and transcoder IP blocks. Second the panel helpers + for handling panel-related information and logic. Plus then a big set of + helpers for the various sink standards (DisplayPort, HDMI, MIPI DSI). Finally + there's also generic helpers for handling output probing, and for dealing with + EDIDs. + +* The last group of helpers concerns itself with the frontend side of a display + pipeline: Planes, handling rectangles for visibility checking and scissoring, + flip queues and assorted bits. + +Modeset Helper Reference for Common Vtables +=========================================== + +.. kernel-doc:: include/drm/drm_modeset_helper_vtables.h + :doc: overview + +.. kernel-doc:: include/drm/drm_modeset_helper_vtables.h + :internal: + +.. _drm_atomic_helper: + +Atomic Modeset Helper Functions Reference +========================================= + +Overview +-------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c + :doc: overview + +Implementing Asynchronous Atomic Commit +--------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c + :doc: implementing nonblocking commit + +Helper Functions Reference +-------------------------- + +.. kernel-doc:: include/drm/drm_atomic_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_helper.c + :export: + +Atomic State Reset and Initialization +------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_state_helper.c + :doc: atomic state reset and initialization + +Atomic State Helper Reference +----------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_state_helper.c + :export: + +Simple KMS Helper Reference +=========================== + +.. kernel-doc:: drivers/gpu/drm/drm_simple_kms_helper.c + :doc: overview + +.. kernel-doc:: include/drm/drm_simple_kms_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_simple_kms_helper.c + :export: + +fbdev Helper Functions Reference +================================ + +.. kernel-doc:: drivers/gpu/drm/drm_fb_helper.c + :doc: fbdev helpers + +.. kernel-doc:: include/drm/drm_fb_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_fb_helper.c + :export: + +format Helper Functions Reference +================================= + +.. kernel-doc:: drivers/gpu/drm/drm_format_helper.c + :export: + +Framebuffer CMA Helper Functions Reference +========================================== + +.. kernel-doc:: drivers/gpu/drm/drm_fb_cma_helper.c + :doc: framebuffer cma helper functions + +.. kernel-doc:: drivers/gpu/drm/drm_fb_cma_helper.c + :export: + +Framebuffer GEM Helper Reference +================================ + +.. kernel-doc:: drivers/gpu/drm/drm_gem_framebuffer_helper.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_gem_framebuffer_helper.c + :export: + +.. _drm_bridges: + +Bridges +======= + +Overview +-------- + +.. kernel-doc:: drivers/gpu/drm/drm_bridge.c + :doc: overview + +Bridge Operations +----------------- + +.. kernel-doc:: drivers/gpu/drm/drm_bridge.c + :doc: bridge operations + +Bridge Connector Helper +----------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_bridge_connector.c + :doc: overview + + +Bridge Helper Reference +------------------------- + +.. kernel-doc:: include/drm/drm_bridge.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_bridge.c + :export: + +Bridge Connector Helper Reference +--------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_bridge_connector.c + :export: + +Panel-Bridge Helper Reference +----------------------------- + +.. kernel-doc:: drivers/gpu/drm/bridge/panel.c + :export: + +.. _drm_panel_helper: + +Panel Helper Reference +====================== + +.. kernel-doc:: drivers/gpu/drm/drm_panel.c + :doc: drm panel + +.. kernel-doc:: include/drm/drm_panel.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_panel.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_panel_orientation_quirks.c + :export: + +Panel Self Refresh Helper Reference +=================================== + +.. kernel-doc:: drivers/gpu/drm/drm_self_refresh_helper.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_self_refresh_helper.c + :export: + +HDCP Helper Functions Reference +=============================== + +.. kernel-doc:: drivers/gpu/drm/drm_hdcp.c + :export: + +Display Port Helper Functions Reference +======================================= + +.. kernel-doc:: drivers/gpu/drm/drm_dp_helper.c + :doc: dp helpers + +.. kernel-doc:: include/drm/drm_dp_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_dp_helper.c + :export: + +Display Port CEC Helper Functions Reference +=========================================== + +.. kernel-doc:: drivers/gpu/drm/drm_dp_cec.c + :doc: dp cec helpers + +.. kernel-doc:: drivers/gpu/drm/drm_dp_cec.c + :export: + +Display Port Dual Mode Adaptor Helper Functions Reference +========================================================= + +.. kernel-doc:: drivers/gpu/drm/drm_dp_dual_mode_helper.c + :doc: dp dual mode helpers + +.. kernel-doc:: include/drm/drm_dp_dual_mode_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_dp_dual_mode_helper.c + :export: + +Display Port MST Helpers +======================== + +Overview +-------- + +.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c + :doc: dp mst helper + +.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c + :doc: Branch device and port refcounting + +Functions Reference +------------------- + +.. kernel-doc:: include/drm/drm_dp_mst_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c + :export: + +Topology Lifetime Internals +--------------------------- + +These functions aren't exported to drivers, but are documented here to help make +the MST topology helpers easier to understand + +.. kernel-doc:: drivers/gpu/drm/drm_dp_mst_topology.c + :functions: drm_dp_mst_topology_try_get_mstb drm_dp_mst_topology_get_mstb + drm_dp_mst_topology_put_mstb + drm_dp_mst_topology_try_get_port drm_dp_mst_topology_get_port + drm_dp_mst_topology_put_port + drm_dp_mst_get_mstb_malloc drm_dp_mst_put_mstb_malloc + +MIPI DBI Helper Functions Reference +=================================== + +.. kernel-doc:: drivers/gpu/drm/drm_mipi_dbi.c + :doc: overview + +.. kernel-doc:: include/drm/drm_mipi_dbi.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_mipi_dbi.c + :export: + +MIPI DSI Helper Functions Reference +=================================== + +.. kernel-doc:: drivers/gpu/drm/drm_mipi_dsi.c + :doc: dsi helpers + +.. kernel-doc:: include/drm/drm_mipi_dsi.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_mipi_dsi.c + :export: + +Display Stream Compression Helper Functions Reference +===================================================== + +.. kernel-doc:: drivers/gpu/drm/drm_dsc.c + :doc: dsc helpers + +.. kernel-doc:: include/drm/drm_dsc.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_dsc.c + :export: + +Output Probing Helper Functions Reference +========================================= + +.. kernel-doc:: drivers/gpu/drm/drm_probe_helper.c + :doc: output probing helper overview + +.. kernel-doc:: drivers/gpu/drm/drm_probe_helper.c + :export: + +EDID Helper Functions Reference +=============================== + +.. kernel-doc:: include/drm/drm_edid.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_edid.c + :export: + +SCDC Helper Functions Reference +=============================== + +.. kernel-doc:: drivers/gpu/drm/drm_scdc_helper.c + :doc: scdc helpers + +.. kernel-doc:: include/drm/drm_scdc_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_scdc_helper.c + :export: + +HDMI Infoframes Helper Reference +================================ + +Strictly speaking this is not a DRM helper library but generally useable +by any driver interfacing with HDMI outputs like v4l or alsa drivers. +But it nicely fits into the overall topic of mode setting helper +libraries and hence is also included here. + +.. kernel-doc:: include/linux/hdmi.h + :internal: + +.. kernel-doc:: drivers/video/hdmi.c + :export: + +Rectangle Utilities Reference +============================= + +.. kernel-doc:: include/drm/drm_rect.h + :doc: rect utils + +.. kernel-doc:: include/drm/drm_rect.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_rect.c + :export: + +Flip-work Helper Reference +========================== + +.. kernel-doc:: include/drm/drm_flip_work.h + :doc: flip utils + +.. kernel-doc:: include/drm/drm_flip_work.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_flip_work.c + :export: + +Auxiliary Modeset Helpers +========================= + +.. kernel-doc:: drivers/gpu/drm/drm_modeset_helper.c + :doc: aux kms helpers + +.. kernel-doc:: drivers/gpu/drm/drm_modeset_helper.c + :export: + +OF/DT Helpers +============= + +.. kernel-doc:: drivers/gpu/drm/drm_of.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_of.c + :export: + +Legacy Plane Helper Reference +============================= + +.. kernel-doc:: drivers/gpu/drm/drm_plane_helper.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_plane_helper.c + :export: + +Legacy CRTC/Modeset Helper Functions Reference +============================================== + +.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c + :export: diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst new file mode 100644 index 000000000..3c5ae4f6d --- /dev/null +++ b/Documentation/gpu/drm-kms.rst @@ -0,0 +1,560 @@ +========================= +Kernel Mode Setting (KMS) +========================= + +Drivers must initialize the mode setting core by calling +drmm_mode_config_init() on the DRM device. The function +initializes the :c:type:`struct drm_device <drm_device>` +mode_config field and never fails. Once done, mode configuration must +be setup by initializing the following fields. + +- int min_width, min_height; int max_width, max_height; + Minimum and maximum width and height of the frame buffers in pixel + units. + +- struct drm_mode_config_funcs \*funcs; + Mode setting functions. + +Overview +======== + +.. kernel-render:: DOT + :alt: KMS Display Pipeline + :caption: KMS Display Pipeline Overview + + digraph "KMS" { + node [shape=box] + + subgraph cluster_static { + style=dashed + label="Static Objects" + + node [bgcolor=grey style=filled] + "drm_plane A" -> "drm_crtc" + "drm_plane B" -> "drm_crtc" + "drm_crtc" -> "drm_encoder A" + "drm_crtc" -> "drm_encoder B" + } + + subgraph cluster_user_created { + style=dashed + label="Userspace-Created" + + node [shape=oval] + "drm_framebuffer 1" -> "drm_plane A" + "drm_framebuffer 2" -> "drm_plane B" + } + + subgraph cluster_connector { + style=dashed + label="Hotpluggable" + + "drm_encoder A" -> "drm_connector A" + "drm_encoder B" -> "drm_connector B" + } + } + +The basic object structure KMS presents to userspace is fairly simple. +Framebuffers (represented by :c:type:`struct drm_framebuffer <drm_framebuffer>`, +see `Frame Buffer Abstraction`_) feed into planes. Planes are represented by +:c:type:`struct drm_plane <drm_plane>`, see `Plane Abstraction`_ for more +details. One or more (or even no) planes feed their pixel data into a CRTC +(represented by :c:type:`struct drm_crtc <drm_crtc>`, see `CRTC Abstraction`_) +for blending. The precise blending step is explained in more detail in `Plane +Composition Properties`_ and related chapters. + +For the output routing the first step is encoders (represented by +:c:type:`struct drm_encoder <drm_encoder>`, see `Encoder Abstraction`_). Those +are really just internal artifacts of the helper libraries used to implement KMS +drivers. Besides that they make it unecessarily more complicated for userspace +to figure out which connections between a CRTC and a connector are possible, and +what kind of cloning is supported, they serve no purpose in the userspace API. +Unfortunately encoders have been exposed to userspace, hence can't remove them +at this point. Futhermore the exposed restrictions are often wrongly set by +drivers, and in many cases not powerful enough to express the real restrictions. +A CRTC can be connected to multiple encoders, and for an active CRTC there must +be at least one encoder. + +The final, and real, endpoint in the display chain is the connector (represented +by :c:type:`struct drm_connector <drm_connector>`, see `Connector +Abstraction`_). Connectors can have different possible encoders, but the kernel +driver selects which encoder to use for each connector. The use case is DVI, +which could switch between an analog and a digital encoder. Encoders can also +drive multiple different connectors. There is exactly one active connector for +every active encoder. + +Internally the output pipeline is a bit more complex and matches today's +hardware more closely: + +.. kernel-render:: DOT + :alt: KMS Output Pipeline + :caption: KMS Output Pipeline + + digraph "Output Pipeline" { + node [shape=box] + + subgraph { + "drm_crtc" [bgcolor=grey style=filled] + } + + subgraph cluster_internal { + style=dashed + label="Internal Pipeline" + { + node [bgcolor=grey style=filled] + "drm_encoder A"; + "drm_encoder B"; + "drm_encoder C"; + } + + { + node [bgcolor=grey style=filled] + "drm_encoder B" -> "drm_bridge B" + "drm_encoder C" -> "drm_bridge C1" + "drm_bridge C1" -> "drm_bridge C2"; + } + } + + "drm_crtc" -> "drm_encoder A" + "drm_crtc" -> "drm_encoder B" + "drm_crtc" -> "drm_encoder C" + + + subgraph cluster_output { + style=dashed + label="Outputs" + + "drm_encoder A" -> "drm_connector A"; + "drm_bridge B" -> "drm_connector B"; + "drm_bridge C2" -> "drm_connector C"; + + "drm_panel" + } + } + +Internally two additional helper objects come into play. First, to be able to +share code for encoders (sometimes on the same SoC, sometimes off-chip) one or +more :ref:`drm_bridges` (represented by :c:type:`struct drm_bridge +<drm_bridge>`) can be linked to an encoder. This link is static and cannot be +changed, which means the cross-bar (if there is any) needs to be mapped between +the CRTC and any encoders. Often for drivers with bridges there's no code left +at the encoder level. Atomic drivers can leave out all the encoder callbacks to +essentially only leave a dummy routing object behind, which is needed for +backwards compatibility since encoders are exposed to userspace. + +The second object is for panels, represented by :c:type:`struct drm_panel +<drm_panel>`, see :ref:`drm_panel_helper`. Panels do not have a fixed binding +point, but are generally linked to the driver private structure that embeds +:c:type:`struct drm_connector <drm_connector>`. + +Note that currently the bridge chaining and interactions with connectors and +panels are still in-flux and not really fully sorted out yet. + +KMS Core Structures and Functions +================================= + +.. kernel-doc:: include/drm/drm_mode_config.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_mode_config.c + :export: + +Modeset Base Object Abstraction +=============================== + +.. kernel-render:: DOT + :alt: Mode Objects and Properties + :caption: Mode Objects and Properties + + digraph { + node [shape=box] + + "drm_property A" -> "drm_mode_object A" + "drm_property A" -> "drm_mode_object B" + "drm_property B" -> "drm_mode_object A" + } + +The base structure for all KMS objects is :c:type:`struct drm_mode_object +<drm_mode_object>`. One of the base services it provides is tracking properties, +which are especially important for the atomic IOCTL (see `Atomic Mode +Setting`_). The somewhat surprising part here is that properties are not +directly instantiated on each object, but free-standing mode objects themselves, +represented by :c:type:`struct drm_property <drm_property>`, which only specify +the type and value range of a property. Any given property can be attached +multiple times to different objects using drm_object_attach_property(). + +.. kernel-doc:: include/drm/drm_mode_object.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_mode_object.c + :export: + +Atomic Mode Setting +=================== + + +.. kernel-render:: DOT + :alt: Mode Objects and Properties + :caption: Mode Objects and Properties + + digraph { + node [shape=box] + + subgraph cluster_state { + style=dashed + label="Free-standing state" + + "drm_atomic_state" -> "duplicated drm_plane_state A" + "drm_atomic_state" -> "duplicated drm_plane_state B" + "drm_atomic_state" -> "duplicated drm_crtc_state" + "drm_atomic_state" -> "duplicated drm_connector_state" + "drm_atomic_state" -> "duplicated driver private state" + } + + subgraph cluster_current { + style=dashed + label="Current state" + + "drm_device" -> "drm_plane A" + "drm_device" -> "drm_plane B" + "drm_device" -> "drm_crtc" + "drm_device" -> "drm_connector" + "drm_device" -> "driver private object" + + "drm_plane A" -> "drm_plane_state A" + "drm_plane B" -> "drm_plane_state B" + "drm_crtc" -> "drm_crtc_state" + "drm_connector" -> "drm_connector_state" + "driver private object" -> "driver private state" + } + + "drm_atomic_state" -> "drm_device" [label="atomic_commit"] + "duplicated drm_plane_state A" -> "drm_device"[style=invis] + } + +Atomic provides transactional modeset (including planes) updates, but a +bit differently from the usual transactional approach of try-commit and +rollback: + +- Firstly, no hardware changes are allowed when the commit would fail. This + allows us to implement the DRM_MODE_ATOMIC_TEST_ONLY mode, which allows + userspace to explore whether certain configurations would work or not. + +- This would still allow setting and rollback of just the software state, + simplifying conversion of existing drivers. But auditing drivers for + correctness of the atomic_check code becomes really hard with that: Rolling + back changes in data structures all over the place is hard to get right. + +- Lastly, for backwards compatibility and to support all use-cases, atomic + updates need to be incremental and be able to execute in parallel. Hardware + doesn't always allow it, but where possible plane updates on different CRTCs + should not interfere, and not get stalled due to output routing changing on + different CRTCs. + +Taken all together there's two consequences for the atomic design: + +- The overall state is split up into per-object state structures: + :c:type:`struct drm_plane_state <drm_plane_state>` for planes, :c:type:`struct + drm_crtc_state <drm_crtc_state>` for CRTCs and :c:type:`struct + drm_connector_state <drm_connector_state>` for connectors. These are the only + objects with userspace-visible and settable state. For internal state drivers + can subclass these structures through embeddeding, or add entirely new state + structures for their globally shared hardware functions, see :c:type:`struct + drm_private_state<drm_private_state>`. + +- An atomic update is assembled and validated as an entirely free-standing pile + of structures within the :c:type:`drm_atomic_state <drm_atomic_state>` + container. Driver private state structures are also tracked in the same + structure; see the next chapter. Only when a state is committed is it applied + to the driver and modeset objects. This way rolling back an update boils down + to releasing memory and unreferencing objects like framebuffers. + +Locking of atomic state structures is internally using :c:type:`struct +drm_modeset_lock <drm_modeset_lock>`. As a general rule the locking shouldn't be +exposed to drivers, instead the right locks should be automatically acquired by +any function that duplicates or peeks into a state, like e.g. +drm_atomic_get_crtc_state(). Locking only protects the software data +structure, ordering of committing state changes to hardware is sequenced using +:c:type:`struct drm_crtc_commit <drm_crtc_commit>`. + +Read on in this chapter, and also in :ref:`drm_atomic_helper` for more detailed +coverage of specific topics. + +Handling Driver Private State +----------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic.c + :doc: handling driver private state + +Atomic Mode Setting Function Reference +-------------------------------------- + +.. kernel-doc:: include/drm/drm_atomic.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_atomic.c + :export: + +Atomic Mode Setting IOCTL and UAPI Functions +-------------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_uapi.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_uapi.c + :export: + +CRTC Abstraction +================ + +.. kernel-doc:: drivers/gpu/drm/drm_crtc.c + :doc: overview + +CRTC Functions Reference +-------------------------------- + +.. kernel-doc:: include/drm/drm_crtc.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_crtc.c + :export: + +Frame Buffer Abstraction +======================== + +.. kernel-doc:: drivers/gpu/drm/drm_framebuffer.c + :doc: overview + +Frame Buffer Functions Reference +-------------------------------- + +.. kernel-doc:: include/drm/drm_framebuffer.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_framebuffer.c + :export: + +DRM Format Handling +=================== + +.. kernel-doc:: include/uapi/drm/drm_fourcc.h + :doc: overview + +Format Functions Reference +-------------------------- + +.. kernel-doc:: include/drm/drm_fourcc.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_fourcc.c + :export: + +Dumb Buffer Objects +=================== + +.. kernel-doc:: drivers/gpu/drm/drm_dumb_buffers.c + :doc: overview + +Plane Abstraction +================= + +.. kernel-doc:: drivers/gpu/drm/drm_plane.c + :doc: overview + +Plane Functions Reference +------------------------- + +.. kernel-doc:: include/drm/drm_plane.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_plane.c + :export: + +Display Modes Function Reference +================================ + +.. kernel-doc:: include/drm/drm_modes.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_modes.c + :export: + +Connector Abstraction +===================== + +.. kernel-doc:: drivers/gpu/drm/drm_connector.c + :doc: overview + +Connector Functions Reference +----------------------------- + +.. kernel-doc:: include/drm/drm_connector.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_connector.c + :export: + +Writeback Connectors +-------------------- + +.. kernel-doc:: include/drm/drm_writeback.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_writeback.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_writeback.c + :export: + +Encoder Abstraction +=================== + +.. kernel-doc:: drivers/gpu/drm/drm_encoder.c + :doc: overview + +Encoder Functions Reference +--------------------------- + +.. kernel-doc:: include/drm/drm_encoder.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_encoder.c + :export: + +KMS Locking +=========== + +.. kernel-doc:: drivers/gpu/drm/drm_modeset_lock.c + :doc: kms locking + +.. kernel-doc:: include/drm/drm_modeset_lock.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_modeset_lock.c + :export: + +KMS Properties +============== + +Property Types and Blob Property Support +---------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_property.c + :doc: overview + +.. kernel-doc:: include/drm/drm_property.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_property.c + :export: + +Standard Connector Properties +----------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_connector.c + :doc: standard connector properties + +HDMI Specific Connector Properties +---------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_connector.c + :doc: HDMI connector properties + +Standard CRTC Properties +------------------------ + +.. kernel-doc:: drivers/gpu/drm/drm_crtc.c + :doc: standard CRTC properties + +Plane Composition Properties +---------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_blend.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_blend.c + :export: + +FB_DAMAGE_CLIPS +~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/drm_damage_helper.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_damage_helper.c + :export: + +.. kernel-doc:: include/drm/drm_damage_helper.h + :internal: + +Color Management Properties +--------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c + :export: + +.. kernel-doc:: include/drm/drm_color_mgmt.h + :internal: + +Tile Group Property +------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_connector.c + :doc: Tile group + +Explicit Fencing Properties +--------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic_uapi.c + :doc: explicit fencing properties + + +Variable Refresh Properties +--------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_connector.c + :doc: Variable refresh properties + +Existing KMS Properties +----------------------- + +The following table gives description of drm properties exposed by various +modules/drivers. Because this table is very unwieldy, do not add any new +properties here. Instead document them in a section above. + +.. csv-table:: + :header-rows: 1 + :file: kms-properties.csv + +Vertical Blanking +================= + +.. kernel-doc:: drivers/gpu/drm/drm_vblank.c + :doc: vblank handling + +Vertical Blanking and Interrupt Handling Functions Reference +------------------------------------------------------------ + +.. kernel-doc:: include/drm/drm_vblank.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_vblank.c + :export: + +Vertical Blank Work +=================== + +.. kernel-doc:: drivers/gpu/drm/drm_vblank_work.c + :doc: vblank works + +Vertical Blank Work Functions Reference +--------------------------------------- + +.. kernel-doc:: include/drm/drm_vblank_work.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_vblank_work.c + :export: diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst new file mode 100644 index 000000000..9abee1589 --- /dev/null +++ b/Documentation/gpu/drm-mm.rst @@ -0,0 +1,506 @@ +===================== +DRM Memory Management +===================== + +Modern Linux systems require large amount of graphics memory to store +frame buffers, textures, vertices and other graphics-related data. Given +the very dynamic nature of many of that data, managing graphics memory +efficiently is thus crucial for the graphics stack and plays a central +role in the DRM infrastructure. + +The DRM core includes two memory managers, namely Translation Table Maps +(TTM) and Graphics Execution Manager (GEM). TTM was the first DRM memory +manager to be developed and tried to be a one-size-fits-them all +solution. It provides a single userspace API to accommodate the need of +all hardware, supporting both Unified Memory Architecture (UMA) devices +and devices with dedicated video RAM (i.e. most discrete video cards). +This resulted in a large, complex piece of code that turned out to be +hard to use for driver development. + +GEM started as an Intel-sponsored project in reaction to TTM's +complexity. Its design philosophy is completely different: instead of +providing a solution to every graphics memory-related problems, GEM +identified common code between drivers and created a support library to +share it. GEM has simpler initialization and execution requirements than +TTM, but has no video RAM management capabilities and is thus limited to +UMA devices. + +The Translation Table Manager (TTM) +=================================== + +TTM design background and information belongs here. + +TTM initialization +------------------ + + **Warning** + This section is outdated. + +Drivers wishing to support TTM must pass a filled :c:type:`ttm_bo_driver +<ttm_bo_driver>` structure to ttm_bo_device_init, together with an +initialized global reference to the memory manager. The ttm_bo_driver +structure contains several fields with function pointers for +initializing the TTM, allocating and freeing memory, waiting for command +completion and fence synchronization, and memory migration. + +The :c:type:`struct drm_global_reference <drm_global_reference>` is made +up of several fields: + +.. code-block:: c + + struct drm_global_reference { + enum ttm_global_types global_type; + size_t size; + void *object; + int (*init) (struct drm_global_reference *); + void (*release) (struct drm_global_reference *); + }; + + +There should be one global reference structure for your memory manager +as a whole, and there will be others for each object created by the +memory manager at runtime. Your global TTM should have a type of +TTM_GLOBAL_TTM_MEM. The size field for the global object should be +sizeof(struct ttm_mem_global), and the init and release hooks should +point at your driver-specific init and release routines, which probably +eventually call ttm_mem_global_init and ttm_mem_global_release, +respectively. + +Once your global TTM accounting structure is set up and initialized by +calling ttm_global_item_ref() on it, you need to create a buffer +object TTM to provide a pool for buffer object allocation by clients and +the kernel itself. The type of this object should be +TTM_GLOBAL_TTM_BO, and its size should be sizeof(struct +ttm_bo_global). Again, driver-specific init and release functions may +be provided, likely eventually calling ttm_bo_global_ref_init() and +ttm_bo_global_ref_release(), respectively. Also, like the previous +object, ttm_global_item_ref() is used to create an initial reference +count for the TTM, which will call your initialization function. + +See the radeon_ttm.c file for an example of usage. + +The Graphics Execution Manager (GEM) +==================================== + +The GEM design approach has resulted in a memory manager that doesn't +provide full coverage of all (or even all common) use cases in its +userspace or kernel API. GEM exposes a set of standard memory-related +operations to userspace and a set of helper functions to drivers, and +let drivers implement hardware-specific operations with their own +private API. + +The GEM userspace API is described in the `GEM - the Graphics Execution +Manager <http://lwn.net/Articles/283798/>`__ article on LWN. While +slightly outdated, the document provides a good overview of the GEM API +principles. Buffer allocation and read and write operations, described +as part of the common GEM API, are currently implemented using +driver-specific ioctls. + +GEM is data-agnostic. It manages abstract buffer objects without knowing +what individual buffers contain. APIs that require knowledge of buffer +contents or purpose, such as buffer allocation or synchronization +primitives, are thus outside of the scope of GEM and must be implemented +using driver-specific ioctls. + +On a fundamental level, GEM involves several operations: + +- Memory allocation and freeing +- Command execution +- Aperture management at command execution time + +Buffer object allocation is relatively straightforward and largely +provided by Linux's shmem layer, which provides memory to back each +object. + +Device-specific operations, such as command execution, pinning, buffer +read & write, mapping, and domain ownership transfers are left to +driver-specific ioctls. + +GEM Initialization +------------------ + +Drivers that use GEM must set the DRIVER_GEM bit in the struct +:c:type:`struct drm_driver <drm_driver>` driver_features +field. The DRM core will then automatically initialize the GEM core +before calling the load operation. Behind the scene, this will create a +DRM Memory Manager object which provides an address space pool for +object allocation. + +In a KMS configuration, drivers need to allocate and initialize a +command ring buffer following core GEM initialization if required by the +hardware. UMA devices usually have what is called a "stolen" memory +region, which provides space for the initial framebuffer and large, +contiguous memory regions required by the device. This space is +typically not managed by GEM, and must be initialized separately into +its own DRM MM object. + +GEM Objects Creation +-------------------- + +GEM splits creation of GEM objects and allocation of the memory that +backs them in two distinct operations. + +GEM objects are represented by an instance of struct :c:type:`struct +drm_gem_object <drm_gem_object>`. Drivers usually need to +extend GEM objects with private information and thus create a +driver-specific GEM object structure type that embeds an instance of +struct :c:type:`struct drm_gem_object <drm_gem_object>`. + +To create a GEM object, a driver allocates memory for an instance of its +specific GEM object type and initializes the embedded struct +:c:type:`struct drm_gem_object <drm_gem_object>` with a call +to drm_gem_object_init(). The function takes a pointer +to the DRM device, a pointer to the GEM object and the buffer object +size in bytes. + +GEM uses shmem to allocate anonymous pageable memory. +drm_gem_object_init() will create an shmfs file of the +requested size and store it into the struct :c:type:`struct +drm_gem_object <drm_gem_object>` filp field. The memory is +used as either main storage for the object when the graphics hardware +uses system memory directly or as a backing store otherwise. + +Drivers are responsible for the actual physical pages allocation by +calling shmem_read_mapping_page_gfp() for each page. +Note that they can decide to allocate pages when initializing the GEM +object, or to delay allocation until the memory is needed (for instance +when a page fault occurs as a result of a userspace memory access or +when the driver needs to start a DMA transfer involving the memory). + +Anonymous pageable memory allocation is not always desired, for instance +when the hardware requires physically contiguous system memory as is +often the case in embedded devices. Drivers can create GEM objects with +no shmfs backing (called private GEM objects) by initializing them with a call +to drm_gem_private_object_init() instead of drm_gem_object_init(). Storage for +private GEM objects must be managed by drivers. + +GEM Objects Lifetime +-------------------- + +All GEM objects are reference-counted by the GEM core. References can be +acquired and release by calling drm_gem_object_get() and drm_gem_object_put() +respectively. + +When the last reference to a GEM object is released the GEM core calls +the :c:type:`struct drm_driver <drm_driver>` gem_free_object_unlocked +operation. That operation is mandatory for GEM-enabled drivers and must +free the GEM object and all associated resources. + +void (\*gem_free_object) (struct drm_gem_object \*obj); Drivers are +responsible for freeing all GEM object resources. This includes the +resources created by the GEM core, which need to be released with +drm_gem_object_release(). + +GEM Objects Naming +------------------ + +Communication between userspace and the kernel refers to GEM objects +using local handles, global names or, more recently, file descriptors. +All of those are 32-bit integer values; the usual Linux kernel limits +apply to the file descriptors. + +GEM handles are local to a DRM file. Applications get a handle to a GEM +object through a driver-specific ioctl, and can use that handle to refer +to the GEM object in other standard or driver-specific ioctls. Closing a +DRM file handle frees all its GEM handles and dereferences the +associated GEM objects. + +To create a handle for a GEM object drivers call drm_gem_handle_create(). The +function takes a pointer to the DRM file and the GEM object and returns a +locally unique handle. When the handle is no longer needed drivers delete it +with a call to drm_gem_handle_delete(). Finally the GEM object associated with a +handle can be retrieved by a call to drm_gem_object_lookup(). + +Handles don't take ownership of GEM objects, they only take a reference +to the object that will be dropped when the handle is destroyed. To +avoid leaking GEM objects, drivers must make sure they drop the +reference(s) they own (such as the initial reference taken at object +creation time) as appropriate, without any special consideration for the +handle. For example, in the particular case of combined GEM object and +handle creation in the implementation of the dumb_create operation, +drivers must drop the initial reference to the GEM object before +returning the handle. + +GEM names are similar in purpose to handles but are not local to DRM +files. They can be passed between processes to reference a GEM object +globally. Names can't be used directly to refer to objects in the DRM +API, applications must convert handles to names and names to handles +using the DRM_IOCTL_GEM_FLINK and DRM_IOCTL_GEM_OPEN ioctls +respectively. The conversion is handled by the DRM core without any +driver-specific support. + +GEM also supports buffer sharing with dma-buf file descriptors through +PRIME. GEM-based drivers must use the provided helpers functions to +implement the exporting and importing correctly. See ?. Since sharing +file descriptors is inherently more secure than the easily guessable and +global GEM names it is the preferred buffer sharing mechanism. Sharing +buffers through GEM names is only supported for legacy userspace. +Furthermore PRIME also allows cross-device buffer sharing since it is +based on dma-bufs. + +GEM Objects Mapping +------------------- + +Because mapping operations are fairly heavyweight GEM favours +read/write-like access to buffers, implemented through driver-specific +ioctls, over mapping buffers to userspace. However, when random access +to the buffer is needed (to perform software rendering for instance), +direct access to the object can be more efficient. + +The mmap system call can't be used directly to map GEM objects, as they +don't have their own file handle. Two alternative methods currently +co-exist to map GEM objects to userspace. The first method uses a +driver-specific ioctl to perform the mapping operation, calling +do_mmap() under the hood. This is often considered +dubious, seems to be discouraged for new GEM-enabled drivers, and will +thus not be described here. + +The second method uses the mmap system call on the DRM file handle. void +\*mmap(void \*addr, size_t length, int prot, int flags, int fd, off_t +offset); DRM identifies the GEM object to be mapped by a fake offset +passed through the mmap offset argument. Prior to being mapped, a GEM +object must thus be associated with a fake offset. To do so, drivers +must call drm_gem_create_mmap_offset() on the object. + +Once allocated, the fake offset value must be passed to the application +in a driver-specific way and can then be used as the mmap offset +argument. + +The GEM core provides a helper method drm_gem_mmap() to +handle object mapping. The method can be set directly as the mmap file +operation handler. It will look up the GEM object based on the offset +value and set the VMA operations to the :c:type:`struct drm_driver +<drm_driver>` gem_vm_ops field. Note that drm_gem_mmap() doesn't map memory to +userspace, but relies on the driver-provided fault handler to map pages +individually. + +To use drm_gem_mmap(), drivers must fill the struct :c:type:`struct drm_driver +<drm_driver>` gem_vm_ops field with a pointer to VM operations. + +The VM operations is a :c:type:`struct vm_operations_struct <vm_operations_struct>` +made up of several fields, the more interesting ones being: + +.. code-block:: c + + struct vm_operations_struct { + void (*open)(struct vm_area_struct * area); + void (*close)(struct vm_area_struct * area); + vm_fault_t (*fault)(struct vm_fault *vmf); + }; + + +The open and close operations must update the GEM object reference +count. Drivers can use the drm_gem_vm_open() and drm_gem_vm_close() helper +functions directly as open and close handlers. + +The fault operation handler is responsible for mapping individual pages +to userspace when a page fault occurs. Depending on the memory +allocation scheme, drivers can allocate pages at fault time, or can +decide to allocate memory for the GEM object at the time the object is +created. + +Drivers that want to map the GEM object upfront instead of handling page +faults can implement their own mmap file operation handler. + +For platforms without MMU the GEM core provides a helper method +drm_gem_cma_get_unmapped_area(). The mmap() routines will call this to get a +proposed address for the mapping. + +To use drm_gem_cma_get_unmapped_area(), drivers must fill the struct +:c:type:`struct file_operations <file_operations>` get_unmapped_area field with +a pointer on drm_gem_cma_get_unmapped_area(). + +More detailed information about get_unmapped_area can be found in +Documentation/admin-guide/mm/nommu-mmap.rst + +Memory Coherency +---------------- + +When mapped to the device or used in a command buffer, backing pages for +an object are flushed to memory and marked write combined so as to be +coherent with the GPU. Likewise, if the CPU accesses an object after the +GPU has finished rendering to the object, then the object must be made +coherent with the CPU's view of memory, usually involving GPU cache +flushing of various kinds. This core CPU<->GPU coherency management is +provided by a device-specific ioctl, which evaluates an object's current +domain and performs any necessary flushing or synchronization to put the +object into the desired coherency domain (note that the object may be +busy, i.e. an active render target; in that case, setting the domain +blocks the client and waits for rendering to complete before performing +any necessary flushing operations). + +Command Execution +----------------- + +Perhaps the most important GEM function for GPU devices is providing a +command execution interface to clients. Client programs construct +command buffers containing references to previously allocated memory +objects, and then submit them to GEM. At that point, GEM takes care to +bind all the objects into the GTT, execute the buffer, and provide +necessary synchronization between clients accessing the same buffers. +This often involves evicting some objects from the GTT and re-binding +others (a fairly expensive operation), and providing relocation support +which hides fixed GTT offsets from clients. Clients must take care not +to submit command buffers that reference more objects than can fit in +the GTT; otherwise, GEM will reject them and no rendering will occur. +Similarly, if several objects in the buffer require fence registers to +be allocated for correct rendering (e.g. 2D blits on pre-965 chips), +care must be taken not to require more fence registers than are +available to the client. Such resource management should be abstracted +from the client in libdrm. + +GEM Function Reference +---------------------- + +.. kernel-doc:: include/drm/drm_gem.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_gem.c + :export: + +GEM CMA Helper Functions Reference +---------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_gem_cma_helper.c + :doc: cma helpers + +.. kernel-doc:: include/drm/drm_gem_cma_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_gem_cma_helper.c + :export: + +GEM SHMEM Helper Function Reference +----------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_gem_shmem_helper.c + :doc: overview + +.. kernel-doc:: include/drm/drm_gem_shmem_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_gem_shmem_helper.c + :export: + +GEM VRAM Helper Functions Reference +----------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_gem_vram_helper.c + :doc: overview + +.. kernel-doc:: include/drm/drm_gem_vram_helper.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_gem_vram_helper.c + :export: + +GEM TTM Helper Functions Reference +----------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_gem_ttm_helper.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_gem_ttm_helper.c + :export: + +VMA Offset Manager +================== + +.. kernel-doc:: drivers/gpu/drm/drm_vma_manager.c + :doc: vma offset manager + +.. kernel-doc:: include/drm/drm_vma_manager.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_vma_manager.c + :export: + +.. _prime_buffer_sharing: + +PRIME Buffer Sharing +==================== + +PRIME is the cross device buffer sharing framework in drm, originally +created for the OPTIMUS range of multi-gpu platforms. To userspace PRIME +buffers are dma-buf based file descriptors. + +Overview and Lifetime Rules +--------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_prime.c + :doc: overview and lifetime rules + +PRIME Helper Functions +---------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_prime.c + :doc: PRIME Helpers + +PRIME Function References +------------------------- + +.. kernel-doc:: include/drm/drm_prime.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_prime.c + :export: + +DRM MM Range Allocator +====================== + +Overview +-------- + +.. kernel-doc:: drivers/gpu/drm/drm_mm.c + :doc: Overview + +LRU Scan/Eviction Support +------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_mm.c + :doc: lru scan roster + +DRM MM Range Allocator Function References +------------------------------------------ + +.. kernel-doc:: include/drm/drm_mm.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_mm.c + :export: + +DRM Cache Handling +================== + +.. kernel-doc:: drivers/gpu/drm/drm_cache.c + :export: + +DRM Sync Objects +=========================== + +.. kernel-doc:: drivers/gpu/drm/drm_syncobj.c + :doc: Overview + +.. kernel-doc:: include/drm/drm_syncobj.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_syncobj.c + :export: + +GPU Scheduler +============= + +Overview +-------- + +.. kernel-doc:: drivers/gpu/drm/scheduler/sched_main.c + :doc: Overview + +Scheduler Function References +----------------------------- + +.. kernel-doc:: include/drm/gpu_scheduler.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/scheduler/sched_main.c + :export: diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst new file mode 100644 index 000000000..7dce175f6 --- /dev/null +++ b/Documentation/gpu/drm-uapi.rst @@ -0,0 +1,461 @@ +.. Copyright 2020 DisplayLink (UK) Ltd. + +=================== +Userland interfaces +=================== + +The DRM core exports several interfaces to applications, generally +intended to be used through corresponding libdrm wrapper functions. In +addition, drivers export device-specific interfaces for use by userspace +drivers & device-aware applications through ioctls and sysfs files. + +External interfaces include: memory mapping, context management, DMA +operations, AGP management, vblank control, fence management, memory +management, and output management. + +Cover generic ioctls and sysfs layout here. We only need high-level +info, since man pages should cover the rest. + +libdrm Device Lookup +==================== + +.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c + :doc: getunique and setversion story + + +.. _drm_primary_node: + +Primary Nodes, DRM Master and Authentication +============================================ + +.. kernel-doc:: drivers/gpu/drm/drm_auth.c + :doc: master and authentication + +.. kernel-doc:: drivers/gpu/drm/drm_auth.c + :export: + +.. kernel-doc:: include/drm/drm_auth.h + :internal: + +Open-Source Userspace Requirements +================================== + +The DRM subsystem has stricter requirements than most other kernel subsystems on +what the userspace side for new uAPI needs to look like. This section here +explains what exactly those requirements are, and why they exist. + +The short summary is that any addition of DRM uAPI requires corresponding +open-sourced userspace patches, and those patches must be reviewed and ready for +merging into a suitable and canonical upstream project. + +GFX devices (both display and render/GPU side) are really complex bits of +hardware, with userspace and kernel by necessity having to work together really +closely. The interfaces, for rendering and modesetting, must be extremely wide +and flexible, and therefore it is almost always impossible to precisely define +them for every possible corner case. This in turn makes it really practically +infeasible to differentiate between behaviour that's required by userspace, and +which must not be changed to avoid regressions, and behaviour which is only an +accidental artifact of the current implementation. + +Without access to the full source code of all userspace users that means it +becomes impossible to change the implementation details, since userspace could +depend upon the accidental behaviour of the current implementation in minute +details. And debugging such regressions without access to source code is pretty +much impossible. As a consequence this means: + +- The Linux kernel's "no regression" policy holds in practice only for + open-source userspace of the DRM subsystem. DRM developers are perfectly fine + if closed-source blob drivers in userspace use the same uAPI as the open + drivers, but they must do so in the exact same way as the open drivers. + Creative (ab)use of the interfaces will, and in the past routinely has, lead + to breakage. + +- Any new userspace interface must have an open-source implementation as + demonstration vehicle. + +The other reason for requiring open-source userspace is uAPI review. Since the +kernel and userspace parts of a GFX stack must work together so closely, code +review can only assess whether a new interface achieves its goals by looking at +both sides. Making sure that the interface indeed covers the use-case fully +leads to a few additional requirements: + +- The open-source userspace must not be a toy/test application, but the real + thing. Specifically it needs to handle all the usual error and corner cases. + These are often the places where new uAPI falls apart and hence essential to + assess the fitness of a proposed interface. + +- The userspace side must be fully reviewed and tested to the standards of that + userspace project. For e.g. mesa this means piglit testcases and review on the + mailing list. This is again to ensure that the new interface actually gets the + job done. The userspace-side reviewer should also provide an Acked-by on the + kernel uAPI patch indicating that they believe the proposed uAPI is sound and + sufficiently documented and validated for userspace's consumption. + +- The userspace patches must be against the canonical upstream, not some vendor + fork. This is to make sure that no one cheats on the review and testing + requirements by doing a quick fork. + +- The kernel patch can only be merged after all the above requirements are met, + but it **must** be merged to either drm-next or drm-misc-next **before** the + userspace patches land. uAPI always flows from the kernel, doing things the + other way round risks divergence of the uAPI definitions and header files. + +These are fairly steep requirements, but have grown out from years of shared +pain and experience with uAPI added hastily, and almost always regretted about +just as fast. GFX devices change really fast, requiring a paradigm shift and +entire new set of uAPI interfaces every few years at least. Together with the +Linux kernel's guarantee to keep existing userspace running for 10+ years this +is already rather painful for the DRM subsystem, with multiple different uAPIs +for the same thing co-existing. If we add a few more complete mistakes into the +mix every year it would be entirely unmanageable. + +.. _drm_render_node: + +Render nodes +============ + +DRM core provides multiple character-devices for user-space to use. +Depending on which device is opened, user-space can perform a different +set of operations (mainly ioctls). The primary node is always created +and called card<num>. Additionally, a currently unused control node, +called controlD<num> is also created. The primary node provides all +legacy operations and historically was the only interface used by +userspace. With KMS, the control node was introduced. However, the +planned KMS control interface has never been written and so the control +node stays unused to date. + +With the increased use of offscreen renderers and GPGPU applications, +clients no longer require running compositors or graphics servers to +make use of a GPU. But the DRM API required unprivileged clients to +authenticate to a DRM-Master prior to getting GPU access. To avoid this +step and to grant clients GPU access without authenticating, render +nodes were introduced. Render nodes solely serve render clients, that +is, no modesetting or privileged ioctls can be issued on render nodes. +Only non-global rendering commands are allowed. If a driver supports +render nodes, it must advertise it via the DRIVER_RENDER DRM driver +capability. If not supported, the primary node must be used for render +clients together with the legacy drmAuth authentication procedure. + +If a driver advertises render node support, DRM core will create a +separate render node called renderD<num>. There will be one render node +per device. No ioctls except PRIME-related ioctls will be allowed on +this node. Especially GEM_OPEN will be explicitly prohibited. Render +nodes are designed to avoid the buffer-leaks, which occur if clients +guess the flink names or mmap offsets on the legacy interface. +Additionally to this basic interface, drivers must mark their +driver-dependent render-only ioctls as DRM_RENDER_ALLOW so render +clients can use them. Driver authors must be careful not to allow any +privileged ioctls on render nodes. + +With render nodes, user-space can now control access to the render node +via basic file-system access-modes. A running graphics server which +authenticates clients on the privileged primary/legacy node is no longer +required. Instead, a client can open the render node and is immediately +granted GPU access. Communication between clients (or servers) is done +via PRIME. FLINK from render node to legacy node is not supported. New +clients must not use the insecure FLINK interface. + +Besides dropping all modeset/global ioctls, render nodes also drop the +DRM-Master concept. There is no reason to associate render clients with +a DRM-Master as they are independent of any graphics server. Besides, +they must work without any running master, anyway. Drivers must be able +to run without a master object if they support render nodes. If, on the +other hand, a driver requires shared state between clients which is +visible to user-space and accessible beyond open-file boundaries, they +cannot support render nodes. + +Device Hot-Unplug +================= + +.. note:: + The following is the plan. Implementation is not there yet + (2020 May). + +Graphics devices (display and/or render) may be connected via USB (e.g. +display adapters or docking stations) or Thunderbolt (e.g. eGPU). An end +user is able to hot-unplug this kind of devices while they are being +used, and expects that the very least the machine does not crash. Any +damage from hot-unplugging a DRM device needs to be limited as much as +possible and userspace must be given the chance to handle it if it wants +to. Ideally, unplugging a DRM device still lets a desktop continue to +run, but that is going to need explicit support throughout the whole +graphics stack: from kernel and userspace drivers, through display +servers, via window system protocols, and in applications and libraries. + +Other scenarios that should lead to the same are: unrecoverable GPU +crash, PCI device disappearing off the bus, or forced unbind of a driver +from the physical device. + +In other words, from userspace perspective everything needs to keep on +working more or less, until userspace stops using the disappeared DRM +device and closes it completely. Userspace will learn of the device +disappearance from the device removed uevent, ioctls returning ENODEV +(or driver-specific ioctls returning driver-specific things), or open() +returning ENXIO. + +Only after userspace has closed all relevant DRM device and dmabuf file +descriptors and removed all mmaps, the DRM driver can tear down its +instance for the device that no longer exists. If the same physical +device somehow comes back in the mean time, it shall be a new DRM +device. + +Similar to PIDs, chardev minor numbers are not recycled immediately. A +new DRM device always picks the next free minor number compared to the +previous one allocated, and wraps around when minor numbers are +exhausted. + +The goal raises at least the following requirements for the kernel and +drivers. + +Requirements for KMS UAPI +------------------------- + +- KMS connectors must change their status to disconnected. + +- Legacy modesets and pageflips, and atomic commits, both real and + TEST_ONLY, and any other ioctls either fail with ENODEV or fake + success. + +- Pending non-blocking KMS operations deliver the DRM events userspace + is expecting. This applies also to ioctls that faked success. + +- open() on a device node whose underlying device has disappeared will + fail with ENXIO. + +- Attempting to create a DRM lease on a disappeared DRM device will + fail with ENODEV. Existing DRM leases remain and work as listed + above. + +Requirements for Render and Cross-Device UAPI +--------------------------------------------- + +- All GPU jobs that can no longer run must have their fences + force-signalled to avoid inflicting hangs on userspace. + The associated error code is ENODEV. + +- Some userspace APIs already define what should happen when the device + disappears (OpenGL, GL ES: `GL_KHR_robustness`_; `Vulkan`_: + VK_ERROR_DEVICE_LOST; etc.). DRM drivers are free to implement this + behaviour the way they see best, e.g. returning failures in + driver-specific ioctls and handling those in userspace drivers, or + rely on uevents, and so on. + +- dmabuf which point to memory that has disappeared will either fail to + import with ENODEV or continue to be successfully imported if it would + have succeeded before the disappearance. See also about memory maps + below for already imported dmabufs. + +- Attempting to import a dmabuf to a disappeared device will either fail + with ENODEV or succeed if it would have succeeded without the + disappearance. + +- open() on a device node whose underlying device has disappeared will + fail with ENXIO. + +.. _GL_KHR_robustness: https://www.khronos.org/registry/OpenGL/extensions/KHR/KHR_robustness.txt +.. _Vulkan: https://www.khronos.org/vulkan/ + +Requirements for Memory Maps +---------------------------- + +Memory maps have further requirements that apply to both existing maps +and maps created after the device has disappeared. If the underlying +memory disappears, the map is created or modified such that reads and +writes will still complete successfully but the result is undefined. +This applies to both userspace mmap()'d memory and memory pointed to by +dmabuf which might be mapped to other devices (cross-device dmabuf +imports). + +Raising SIGBUS is not an option, because userspace cannot realistically +handle it. Signal handlers are global, which makes them extremely +difficult to use correctly from libraries like those that Mesa produces. +Signal handlers are not composable, you can't have different handlers +for GPU1 and GPU2 from different vendors, and a third handler for +mmapped regular files. Threads cause additional pain with signal +handling as well. + +.. _drm_driver_ioctl: + +IOCTL Support on Device Nodes +============================= + +.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c + :doc: driver specific ioctls + +Recommended IOCTL Return Values +------------------------------- + +In theory a driver's IOCTL callback is only allowed to return very few error +codes. In practice it's good to abuse a few more. This section documents common +practice within the DRM subsystem: + +ENOENT: + Strictly this should only be used when a file doesn't exist e.g. when + calling the open() syscall. We reuse that to signal any kind of object + lookup failure, e.g. for unknown GEM buffer object handles, unknown KMS + object handles and similar cases. + +ENOSPC: + Some drivers use this to differentiate "out of kernel memory" from "out + of VRAM". Sometimes also applies to other limited gpu resources used for + rendering (e.g. when you have a special limited compression buffer). + Sometimes resource allocation/reservation issues in command submission + IOCTLs are also signalled through EDEADLK. + + Simply running out of kernel/system memory is signalled through ENOMEM. + +EPERM/EACCES: + Returned for an operation that is valid, but needs more privileges. + E.g. root-only or much more common, DRM master-only operations return + this when called by unpriviledged clients. There's no clear + difference between EACCES and EPERM. + +ENODEV: + The device is not present anymore or is not yet fully initialized. + +EOPNOTSUPP: + Feature (like PRIME, modesetting, GEM) is not supported by the driver. + +ENXIO: + Remote failure, either a hardware transaction (like i2c), but also used + when the exporting driver of a shared dma-buf or fence doesn't support a + feature needed. + +EINTR: + DRM drivers assume that userspace restarts all IOCTLs. Any DRM IOCTL can + return EINTR and in such a case should be restarted with the IOCTL + parameters left unchanged. + +EIO: + The GPU died and couldn't be resurrected through a reset. Modesetting + hardware failures are signalled through the "link status" connector + property. + +EINVAL: + Catch-all for anything that is an invalid argument combination which + cannot work. + +IOCTL also use other error codes like ETIME, EFAULT, EBUSY, ENOTTY but their +usage is in line with the common meanings. The above list tries to just document +DRM specific patterns. Note that ENOTTY has the slightly unintuitive meaning of +"this IOCTL does not exist", and is used exactly as such in DRM. + +.. kernel-doc:: include/drm/drm_ioctl.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c + :export: + +.. kernel-doc:: drivers/gpu/drm/drm_ioc32.c + :export: + +Testing and validation +====================== + +Testing Requirements for userspace API +-------------------------------------- + +New cross-driver userspace interface extensions, like new IOCTL, new KMS +properties, new files in sysfs or anything else that constitutes an API change +should have driver-agnostic testcases in IGT for that feature, if such a test +can be reasonably made using IGT for the target hardware. + +Validating changes with IGT +--------------------------- + +There's a collection of tests that aims to cover the whole functionality of +DRM drivers and that can be used to check that changes to DRM drivers or the +core don't regress existing functionality. This test suite is called IGT and +its code and instructions to build and run can be found in +https://gitlab.freedesktop.org/drm/igt-gpu-tools/. + +Using VKMS to test DRM API +-------------------------- + +VKMS is a software-only model of a KMS driver that is useful for testing +and for running compositors. VKMS aims to enable a virtual display without +the need for a hardware display capability. These characteristics made VKMS +a perfect tool for validating the DRM core behavior and also support the +compositor developer. VKMS makes it possible to test DRM functions in a +virtual machine without display, simplifying the validation of some of the +core changes. + +To Validate changes in DRM API with VKMS, start setting the kernel: make +sure to enable VKMS module; compile the kernel with the VKMS enabled and +install it in the target machine. VKMS can be run in a Virtual Machine +(QEMU, virtme or similar). It's recommended the use of KVM with the minimum +of 1GB of RAM and four cores. + +It's possible to run the IGT-tests in a VM in two ways: + + 1. Use IGT inside a VM + 2. Use IGT from the host machine and write the results in a shared directory. + +As follow, there is an example of using a VM with a shared directory with +the host machine to run igt-tests. As an example it's used virtme:: + + $ virtme-run --rwdir /path/for/shared_dir --kdir=path/for/kernel/directory --mods=auto + +Run the igt-tests in the guest machine, as example it's ran the 'kms_flip' +tests:: + + $ /path/for/igt-gpu-tools/scripts/run-tests.sh -p -s -t "kms_flip.*" -v + +In this example, instead of build the igt_runner, Piglit is used +(-p option); it's created html summary of the tests results and it's saved +in the folder "igt-gpu-tools/results"; it's executed only the igt-tests +matching the -t option. + +Display CRC Support +------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_debugfs_crc.c + :doc: CRC ABI + +.. kernel-doc:: drivers/gpu/drm/drm_debugfs_crc.c + :export: + +Debugfs Support +--------------- + +.. kernel-doc:: include/drm/drm_debugfs.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_debugfs.c + :export: + +Sysfs Support +============= + +.. kernel-doc:: drivers/gpu/drm/drm_sysfs.c + :doc: overview + +.. kernel-doc:: drivers/gpu/drm/drm_sysfs.c + :export: + + +VBlank event handling +===================== + +The DRM core exposes two vertical blank related ioctls: + +DRM_IOCTL_WAIT_VBLANK + This takes a struct drm_wait_vblank structure as its argument, and + it is used to block or request a signal when a specified vblank + event occurs. + +DRM_IOCTL_MODESET_CTL + This was only used for user-mode-settind drivers around modesetting + changes to allow the kernel to update the vblank interrupt after + mode setting, since on many devices the vertical blank counter is + reset to 0 at some point during modeset. Modern drivers should not + call this any more since with kernel mode setting it is a no-op. + +Userspace API Structures +======================== + +.. kernel-doc:: include/uapi/drm/drm_mode.h + :doc: overview + +.. kernel-doc:: include/uapi/drm/drm_mode.h + :internal: diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst new file mode 100644 index 000000000..cff1f154b --- /dev/null +++ b/Documentation/gpu/i915.rst @@ -0,0 +1,682 @@ +=========================== + drm/i915 Intel GFX Driver +=========================== + +The drm/i915 driver supports all (with the exception of some very early +models) integrated GFX chipsets with both Intel display and rendering +blocks. This excludes a set of SoC platforms with an SGX rendering unit, +those have basic support through the gma500 drm driver. + +Core Driver Infrastructure +========================== + +This section covers core driver infrastructure used by both the display +and the GEM parts of the driver. + +Runtime Power Management +------------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/intel_runtime_pm.c + :doc: runtime pm + +.. kernel-doc:: drivers/gpu/drm/i915/intel_runtime_pm.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/intel_uncore.c + :internal: + +Interrupt Handling +------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c + :doc: interrupt handling + +.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c + :functions: intel_irq_init intel_irq_init_hw intel_hpd_init + +.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c + :functions: intel_runtime_pm_disable_interrupts + +.. kernel-doc:: drivers/gpu/drm/i915/i915_irq.c + :functions: intel_runtime_pm_enable_interrupts + +Intel GVT-g Guest Support(vGPU) +------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c + :doc: Intel GVT-g guest support + +.. kernel-doc:: drivers/gpu/drm/i915/i915_vgpu.c + :internal: + +Intel GVT-g Host Support(vGPU device model) +------------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/intel_gvt.c + :doc: Intel GVT-g host support + +.. kernel-doc:: drivers/gpu/drm/i915/intel_gvt.c + :internal: + +Workarounds +----------- + +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_workarounds.c + :doc: Hardware workarounds + +Display Hardware Handling +========================= + +This section covers everything related to the display hardware including +the mode setting infrastructure, plane, sprite and cursor handling and +display, output probing and related topics. + +Mode Setting Infrastructure +--------------------------- + +The i915 driver is thus far the only DRM driver which doesn't use the +common DRM helper code to implement mode setting sequences. Thus it has +its own tailor-made infrastructure for executing a display configuration +change. + +Frontbuffer Tracking +-------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_frontbuffer.c + :doc: frontbuffer tracking + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_frontbuffer.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_frontbuffer.c + :internal: + +Display FIFO Underrun Reporting +------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_fifo_underrun.c + :doc: fifo underrun handling + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_fifo_underrun.c + :internal: + +Plane Configuration +------------------- + +This section covers plane configuration and composition with the primary +plane, sprites, cursors and overlays. This includes the infrastructure +to do atomic vsync'ed updates of all this state and also tightly coupled +topics like watermark setup and computation, framebuffer compression and +panel self refresh. + +Atomic Plane Helpers +-------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_atomic_plane.c + :doc: atomic plane helpers + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_atomic_plane.c + :internal: + +Output Probing +-------------- + +This section covers output probing and related infrastructure like the +hotplug interrupt storm detection and mitigation code. Note that the +i915 driver still uses most of the common DRM helper code for output +probing, so those sections fully apply. + +Hotplug +------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_hotplug.c + :doc: Hotplug + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_hotplug.c + :internal: + +High Definition Audio +--------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_audio.c + :doc: High Definition Audio over HDMI and Display Port + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_audio.c + :internal: + +.. kernel-doc:: include/drm/i915_component.h + :internal: + +Intel HDMI LPE Audio Support +---------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_lpe_audio.c + :doc: LPE Audio integration for HDMI or DP playback + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_lpe_audio.c + :internal: + +Panel Self Refresh PSR (PSR/SRD) +-------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_psr.c + :doc: Panel Self Refresh (PSR/SRD) + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_psr.c + :internal: + +Frame Buffer Compression (FBC) +------------------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_fbc.c + :doc: Frame Buffer Compression (FBC) + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_fbc.c + :internal: + +Display Refresh Rate Switching (DRRS) +------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dp.c + :doc: Display Refresh Rate Switching (DRRS) + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dp.c + :functions: intel_dp_set_drrs_state + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dp.c + :functions: intel_edp_drrs_enable + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dp.c + :functions: intel_edp_drrs_disable + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dp.c + :functions: intel_edp_drrs_invalidate + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dp.c + :functions: intel_edp_drrs_flush + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dp.c + :functions: intel_dp_drrs_init + +DPIO +---- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpio_phy.c + :doc: DPIO + +CSR firmware support for DMC +---------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_csr.c + :doc: csr support for dmc + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_csr.c + :internal: + +Video BIOS Table (VBT) +---------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_bios.c + :doc: Video BIOS Table (VBT) + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_bios.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_vbt_defs.h + :internal: + +Display clocks +-------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_cdclk.c + :doc: CDCLK / RAWCLK + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_cdclk.c + :internal: + +Display PLLs +------------ + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpll_mgr.c + :doc: Display PLLs + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpll_mgr.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpll_mgr.h + :internal: + +Display State Buffer +-------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dsb.c + :doc: DSB + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dsb.c + :internal: + +Memory Management and Command Submission +======================================== + +This sections covers all things related to the GEM implementation in the +i915 driver. + +Intel GPU Basics +---------------- + +An Intel GPU has multiple engines. There are several engine types. + +- RCS engine is for rendering 3D and performing compute, this is named + `I915_EXEC_RENDER` in user space. +- BCS is a blitting (copy) engine, this is named `I915_EXEC_BLT` in user + space. +- VCS is a video encode and decode engine, this is named `I915_EXEC_BSD` + in user space +- VECS is video enhancement engine, this is named `I915_EXEC_VEBOX` in user + space. +- The enumeration `I915_EXEC_DEFAULT` does not refer to specific engine; + instead it is to be used by user space to specify a default rendering + engine (for 3D) that may or may not be the same as RCS. + +The Intel GPU family is a family of integrated GPU's using Unified +Memory Access. For having the GPU "do work", user space will feed the +GPU batch buffers via one of the ioctls `DRM_IOCTL_I915_GEM_EXECBUFFER2` +or `DRM_IOCTL_I915_GEM_EXECBUFFER2_WR`. Most such batchbuffers will +instruct the GPU to perform work (for example rendering) and that work +needs memory from which to read and memory to which to write. All memory +is encapsulated within GEM buffer objects (usually created with the ioctl +`DRM_IOCTL_I915_GEM_CREATE`). An ioctl providing a batchbuffer for the GPU +to create will also list all GEM buffer objects that the batchbuffer reads +and/or writes. For implementation details of memory management see +`GEM BO Management Implementation Details`_. + +The i915 driver allows user space to create a context via the ioctl +`DRM_IOCTL_I915_GEM_CONTEXT_CREATE` which is identified by a 32-bit +integer. Such a context should be viewed by user-space as -loosely- +analogous to the idea of a CPU process of an operating system. The i915 +driver guarantees that commands issued to a fixed context are to be +executed so that writes of a previously issued command are seen by +reads of following commands. Actions issued between different contexts +(even if from the same file descriptor) are NOT given that guarantee +and the only way to synchronize across contexts (even from the same +file descriptor) is through the use of fences. At least as far back as +Gen4, also have that a context carries with it a GPU HW context; +the HW context is essentially (most of atleast) the state of a GPU. +In addition to the ordering guarantees, the kernel will restore GPU +state via HW context when commands are issued to a context, this saves +user space the need to restore (most of atleast) the GPU state at the +start of each batchbuffer. The non-deprecated ioctls to submit batchbuffer +work can pass that ID (in the lower bits of drm_i915_gem_execbuffer2::rsvd1) +to identify what context to use with the command. + +The GPU has its own memory management and address space. The kernel +driver maintains the memory translation table for the GPU. For older +GPUs (i.e. those before Gen8), there is a single global such translation +table, a global Graphics Translation Table (GTT). For newer generation +GPUs each context has its own translation table, called Per-Process +Graphics Translation Table (PPGTT). Of important note, is that although +PPGTT is named per-process it is actually per context. When user space +submits a batchbuffer, the kernel walks the list of GEM buffer objects +used by the batchbuffer and guarantees that not only is the memory of +each such GEM buffer object resident but it is also present in the +(PP)GTT. If the GEM buffer object is not yet placed in the (PP)GTT, +then it is given an address. Two consequences of this are: the kernel +needs to edit the batchbuffer submitted to write the correct value of +the GPU address when a GEM BO is assigned a GPU address and the kernel +might evict a different GEM BO from the (PP)GTT to make address room +for another GEM BO. Consequently, the ioctls submitting a batchbuffer +for execution also include a list of all locations within buffers that +refer to GPU-addresses so that the kernel can edit the buffer correctly. +This process is dubbed relocation. + +Locking Guidelines +------------------ + +.. note:: + This is a description of how the locking should be after + refactoring is done. Does not necessarily reflect what the locking + looks like while WIP. + +#. All locking rules and interface contracts with cross-driver interfaces + (dma-buf, dma_fence) need to be followed. + +#. No struct_mutex anywhere in the code + +#. dma_resv will be the outermost lock (when needed) and ww_acquire_ctx + is to be hoisted at highest level and passed down within i915_gem_ctx + in the call chain + +#. While holding lru/memory manager (buddy, drm_mm, whatever) locks + system memory allocations are not allowed + + * Enforce this by priming lockdep (with fs_reclaim). If we + allocate memory while holding these looks we get a rehash + of the shrinker vs. struct_mutex saga, and that would be + real bad. + +#. Do not nest different lru/memory manager locks within each other. + Take them in turn to update memory allocations, relying on the object’s + dma_resv ww_mutex to serialize against other operations. + +#. The suggestion for lru/memory managers locks is that they are small + enough to be spinlocks. + +#. All features need to come with exhaustive kernel selftests and/or + IGT tests when appropriate + +#. All LMEM uAPI paths need to be fully restartable (_interruptible() + for all locks/waits/sleeps) + + * Error handling validation through signal injection. + Still the best strategy we have for validating GEM uAPI + corner cases. + Must be excessively used in the IGT, and we need to check + that we really have full path coverage of all error cases. + + * -EDEADLK handling with ww_mutex + +GEM BO Management Implementation Details +---------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_vma_types.h + :doc: Virtual Memory Address + +Buffer Object Eviction +---------------------- + +This section documents the interface functions for evicting buffer +objects to make space available in the virtual gpu address spaces. Note +that this is mostly orthogonal to shrinking buffer objects caches, which +has the goal to make main memory (shared with the gpu through the +unified memory architecture) available. + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_evict.c + :internal: + +Buffer Object Memory Shrinking +------------------------------ + +This section documents the interface function for shrinking memory usage +of buffer object caches. Shrinking is used to make main memory +available. Note that this is mostly orthogonal to evicting buffer +objects, which has the goal to make space in gpu virtual address spaces. + +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_shrinker.c + :internal: + +Batchbuffer Parsing +------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c + :doc: batch buffer command parser + +.. kernel-doc:: drivers/gpu/drm/i915/i915_cmd_parser.c + :internal: + +User Batchbuffer Execution +-------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c + :doc: User command execution + +Logical Rings, Logical Ring Contexts and Execlists +-------------------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_lrc.c + :doc: Logical Rings, Logical Ring Contexts and Execlists + +Global GTT views +---------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_vma_types.h + :doc: Global GTT views + +.. kernel-doc:: drivers/gpu/drm/i915/i915_gem_gtt.c + :internal: + +GTT Fences and Swizzling +------------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c + :internal: + +Global GTT Fence Handling +~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c + :doc: fence register handling + +Hardware Tiling and Swizzling Details +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c + :doc: tiling swizzling details + +Object Tiling IOCTLs +-------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_tiling.c + :internal: + +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_tiling.c + :doc: buffer object tiling + +Microcontrollers +================ + +Starting from gen9, three microcontrollers are available on the HW: the +graphics microcontroller (GuC), the HEVC/H.265 microcontroller (HuC) and the +display microcontroller (DMC). The driver is responsible for loading the +firmwares on the microcontrollers; the GuC and HuC firmwares are transferred +to WOPCM using the DMA engine, while the DMC firmware is written through MMIO. + +WOPCM +----- + +WOPCM Layout +~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/intel_wopcm.c + :doc: WOPCM Layout + +GuC +--- + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c + :doc: GuC + +GuC Firmware Layout +~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_uc_fw_abi.h + :doc: Firmware Layout + +GuC Memory Management +~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c + :doc: GuC Memory Management +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c + :functions: intel_guc_allocate_vma + + +GuC-specific firmware loader +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc_fw.c + :internal: + +GuC-based command submission +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c + :doc: GuC-based command submission + +HuC +--- +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c + :doc: HuC +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c + :functions: intel_huc_auth + +HuC Memory Management +~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_huc.c + :doc: HuC Memory Management + +HuC Firmware Layout +~~~~~~~~~~~~~~~~~~~ +The HuC FW layout is the same as the GuC one, see `GuC Firmware Layout`_ + +DMC +--- +See `CSR firmware support for DMC`_ + +Tracing +======= + +This sections covers all things related to the tracepoints implemented +in the i915 driver. + +i915_ppgtt_create and i915_ppgtt_release +---------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h + :doc: i915_ppgtt_create and i915_ppgtt_release tracepoints + +i915_context_create and i915_context_free +----------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h + :doc: i915_context_create and i915_context_free tracepoints + +Perf +==== + +Overview +-------- +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :doc: i915 Perf Overview + +Comparison with Core Perf +------------------------- +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :doc: i915 Perf History and Comparison with Core Perf + +i915 Driver Entry Points +------------------------ + +This section covers the entrypoints exported outside of i915_perf.c to +integrate with drm/i915 and to handle the `DRM_I915_PERF_OPEN` ioctl. + +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_init +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_fini +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_register +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_unregister +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_open_ioctl +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_release +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_add_config_ioctl +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_remove_config_ioctl + +i915 Perf Stream +---------------- + +This section covers the stream-semantics-agnostic structures and functions +for representing an i915 perf stream FD and associated file operations. + +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h + :functions: i915_perf_stream +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h + :functions: i915_perf_stream_ops + +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: read_properties_unlocked +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_open_ioctl_locked +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_destroy_locked +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_read +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_ioctl +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_enable_locked +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_disable_locked +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_poll +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_perf_poll_locked + +i915 Perf Observation Architecture Stream +----------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf_types.h + :functions: i915_oa_ops + +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_oa_stream_init +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_oa_read +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_oa_stream_enable +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_oa_stream_disable +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_oa_wait_unlocked +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :functions: i915_oa_poll_wait + +Other i915 Perf Internals +------------------------- + +This section simply includes all other currently documented i915 perf internals, +in no particular order, but may include some more minor utilities or platform +specific details than found in the more high-level sections. + +.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c + :internal: + :no-identifiers: + i915_perf_init + i915_perf_fini + i915_perf_register + i915_perf_unregister + i915_perf_open_ioctl + i915_perf_release + i915_perf_add_config_ioctl + i915_perf_remove_config_ioctl + read_properties_unlocked + i915_perf_open_ioctl_locked + i915_perf_destroy_locked + i915_perf_read i915_perf_ioctl + i915_perf_enable_locked + i915_perf_disable_locked + i915_perf_poll i915_perf_poll_locked + i915_oa_stream_init i915_oa_read + i915_oa_stream_enable + i915_oa_stream_disable + i915_oa_wait_unlocked + i915_oa_poll_wait + +Style +===== + +The drm/i915 driver codebase has some style rules in addition to (and, in some +cases, deviating from) the kernel coding style. + +Register macro definition style +------------------------------- + +The style guide for ``i915_reg.h``. + +.. kernel-doc:: drivers/gpu/drm/i915/i915_reg.h + :doc: The i915 register macro definition style guide diff --git a/Documentation/gpu/index.rst b/Documentation/gpu/index.rst new file mode 100644 index 000000000..c9a51e3bf --- /dev/null +++ b/Documentation/gpu/index.rst @@ -0,0 +1,25 @@ +================================== +Linux GPU Driver Developer's Guide +================================== + +.. toctree:: + + introduction + drm-internals + drm-mm + drm-kms + drm-kms-helpers + drm-uapi + drm-client + drivers + backlight + vga-switcheroo + vgaarbiter + todo + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/gpu/introduction.rst b/Documentation/gpu/introduction.rst new file mode 100644 index 000000000..25a56e9c0 --- /dev/null +++ b/Documentation/gpu/introduction.rst @@ -0,0 +1,114 @@ +============ +Introduction +============ + +The Linux DRM layer contains code intended to support the needs of +complex graphics devices, usually containing programmable pipelines well +suited to 3D graphics acceleration. Graphics drivers in the kernel may +make use of DRM functions to make tasks like memory management, +interrupt handling and DMA easier, and provide a uniform interface to +applications. + +A note on versions: this guide covers features found in the DRM tree, +including the TTM memory manager, output configuration and mode setting, +and the new vblank internals, in addition to all the regular features +found in current kernels. + +[Insert diagram of typical DRM stack here] + +Style Guidelines +================ + +For consistency this documentation uses American English. Abbreviations +are written as all-uppercase, for example: DRM, KMS, IOCTL, CRTC, and so +on. To aid in reading, documentations make full use of the markup +characters kerneldoc provides: @parameter for function parameters, +@member for structure members (within the same structure), &struct structure to +reference structures and function() for functions. These all get automatically +hyperlinked if kerneldoc for the referenced objects exists. When referencing +entries in function vtables (and structure members in general) please use +&vtable_name.vfunc. Unfortunately this does not yet yield a direct link to the +member, only the structure. + +Except in special situations (to separate locked from unlocked variants) +locking requirements for functions aren't documented in the kerneldoc. +Instead locking should be check at runtime using e.g. +``WARN_ON(!mutex_is_locked(...));``. Since it's much easier to ignore +documentation than runtime noise this provides more value. And on top of +that runtime checks do need to be updated when the locking rules change, +increasing the chances that they're correct. Within the documentation +the locking rules should be explained in the relevant structures: Either +in the comment for the lock explaining what it protects, or data fields +need a note about which lock protects them, or both. + +Functions which have a non-\ ``void`` return value should have a section +called "Returns" explaining the expected return values in different +cases and their meanings. Currently there's no consensus whether that +section name should be all upper-case or not, and whether it should end +in a colon or not. Go with the file-local style. Other common section +names are "Notes" with information for dangerous or tricky corner cases, +and "FIXME" where the interface could be cleaned up. + +Also read the :ref:`guidelines for the kernel documentation at large <doc_guide>`. + +Documentation Requirements for kAPI +----------------------------------- + +All kernel APIs exported to other modules must be documented, including their +datastructures and at least a short introductory section explaining the overall +concepts. Documentation should be put into the code itself as kerneldoc comments +as much as reasonable. + +Do not blindly document everything, but document only what's relevant for driver +authors: Internal functions of drm.ko and definitely static functions should not +have formal kerneldoc comments. Use normal C comments if you feel like a comment +is warranted. You may use kerneldoc syntax in the comment, but it shall not +start with a /** kerneldoc marker. Similar for data structures, annotate +anything entirely private with ``/* private: */`` comments as per the +documentation guide. + +Getting Started +=============== + +Developers interested in helping out with the DRM subsystem are very welcome. +Often people will resort to sending in patches for various issues reported by +checkpatch or sparse. We welcome such contributions. + +Anyone looking to kick it up a notch can find a list of janitorial tasks on +the :ref:`TODO list <todo>`. + +Contribution Process +==================== + +Mostly the DRM subsystem works like any other kernel subsystem, see :ref:`the +main process guidelines and documentation <process_index>` for how things work. +Here we just document some of the specialities of the GPU subsystem. + +Feature Merge Deadlines +----------------------- + +All feature work must be in the linux-next tree by the -rc6 release of the +current release cycle, otherwise they must be postponed and can't reach the next +merge window. All patches must have landed in the drm-next tree by latest -rc7, +but if your branch is not in linux-next then this must have happened by -rc6 +already. + +After that point only bugfixes (like after the upstream merge window has closed +with the -rc1 release) are allowed. No new platform enabling or new drivers are +allowed. + +This means that there's a blackout-period of about one month where feature work +can't be merged. The recommended way to deal with that is having a -next tree +that's always open, but making sure to not feed it into linux-next during the +blackout period. As an example, drm-misc works like that. + +Code of Conduct +--------------- + +As a freedesktop.org project, dri-devel, and the DRM community, follows the +Contributor Covenant, found at: https://www.freedesktop.org/wiki/CodeOfConduct + +Please conduct yourself in a respectful and civilised manner when +interacting with community members on mailing lists, IRC, or bug +trackers. The community represents the project as a whole, and abusive +or bullying behaviour is not tolerated by the project. diff --git a/Documentation/gpu/kms-properties.csv b/Documentation/gpu/kms-properties.csv new file mode 100644 index 000000000..07ed22ea3 --- /dev/null +++ b/Documentation/gpu/kms-properties.csv @@ -0,0 +1,101 @@ +Owner Module/Drivers,Group,Property Name,Type,Property Values,Object attached,Description/Restrictions +,DVI-I,“subconnector”,ENUM,"{ “Unknown”, “DVI-D”, “DVI-A” }",Connector,TBD +,,“select subconnector”,ENUM,"{ “Automatic”, “DVI-D”, “DVI-A” }",Connector,TBD +,TV,“subconnector”,ENUM,"{ ""Unknown"", ""Composite"", ""SVIDEO"", ""Component"", ""SCART"" }",Connector,TBD +,,“select subconnector”,ENUM,"{ ""Automatic"", ""Composite"", ""SVIDEO"", ""Component"", ""SCART"" }",Connector,TBD +,,“mode”,ENUM,"{ ""NTSC_M"", ""NTSC_J"", ""NTSC_443"", ""PAL_B"" } etc.",Connector,TBD +,,“left margin”,RANGE,"Min=0, Max=100",Connector,TBD +,,“right margin”,RANGE,"Min=0, Max=100",Connector,TBD +,,“top margin”,RANGE,"Min=0, Max=100",Connector,TBD +,,“bottom margin”,RANGE,"Min=0, Max=100",Connector,TBD +,,“brightness”,RANGE,"Min=0, Max=100",Connector,TBD +,,“contrast”,RANGE,"Min=0, Max=100",Connector,TBD +,,“flicker reduction”,RANGE,"Min=0, Max=100",Connector,TBD +,,“overscan”,RANGE,"Min=0, Max=100",Connector,TBD +,,“saturation”,RANGE,"Min=0, Max=100",Connector,TBD +,,“hue”,RANGE,"Min=0, Max=100",Connector,TBD +,Virtual GPU,“suggested X”,RANGE,"Min=0, Max=0xffffffff",Connector,property to suggest an X offset for a connector +,,“suggested Y”,RANGE,"Min=0, Max=0xffffffff",Connector,property to suggest an Y offset for a connector +,Optional,"""aspect ratio""",ENUM,"{ ""None"", ""4:3"", ""16:9"" }",Connector,TDB +i915,Generic,"""Broadcast RGB""",ENUM,"{ ""Automatic"", ""Full"", ""Limited 16:235"" }",Connector,"When this property is set to Limited 16:235 and CTM is set, the hardware will be programmed with the result of the multiplication of CTM by the limited range matrix to ensure the pixels normaly in the range 0..1.0 are remapped to the range 16/255..235/255." +,,“audio”,ENUM,"{ ""force-dvi"", ""off"", ""auto"", ""on"" }",Connector,TBD +,SDVO-TV,“mode”,ENUM,"{ ""NTSC_M"", ""NTSC_J"", ""NTSC_443"", ""PAL_B"" } etc.",Connector,TBD +,,"""left_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""right_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""top_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""bottom_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“hpos”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“vpos”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“contrast”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“saturation”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“hue”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“sharpness”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter_adaptive”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter_2d”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“tv_chroma_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“tv_luma_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“dot_crawl”,RANGE,"Min=0, Max=1",Connector,TBD +,SDVO-TV/LVDS,“brightness”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +CDV gma-500,Generic,"""Broadcast RGB""",ENUM,"{ “Full”, “Limited 16:235” }",Connector,TBD +,,"""Broadcast RGB""",ENUM,"{ “off”, “auto”, “on” }",Connector,TBD +Poulsbo,Generic,“backlight”,RANGE,"Min=0, Max=100",Connector,TBD +,SDVO-TV,“mode”,ENUM,"{ ""NTSC_M"", ""NTSC_J"", ""NTSC_443"", ""PAL_B"" } etc.",Connector,TBD +,,"""left_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""right_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""top_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,"""bottom_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“hpos”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“vpos”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“contrast”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“saturation”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“hue”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“sharpness”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter_adaptive”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“flicker_filter_2d”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“tv_chroma_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“tv_luma_filter”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +,,“dot_crawl”,RANGE,"Min=0, Max=1",Connector,TBD +,SDVO-TV/LVDS,“brightness”,RANGE,"Min=0, Max= SDVO dependent",Connector,TBD +armada,CRTC,"""CSC_YUV""",ENUM,"{ ""Auto"" , ""CCIR601"", ""CCIR709"" }",CRTC,TBD +,,"""CSC_RGB""",ENUM,"{ ""Auto"", ""Computer system"", ""Studio"" }",CRTC,TBD +,Overlay,"""colorkey""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_min""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_max""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_val""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_alpha""",RANGE,"Min=0, Max=0xffffff",Plane,TBD +,,"""colorkey_mode""",ENUM,"{ ""disabled"", ""Y component"", ""U component"" , ""V component"", ""RGB"", “R component"", ""G component"", ""B component"" }",Plane,TBD +,,"""brightness""",RANGE,"Min=0, Max=256 + 255",Plane,TBD +,,"""contrast""",RANGE,"Min=0, Max=0x7fff",Plane,TBD +,,"""saturation""",RANGE,"Min=0, Max=0x7fff",Plane,TBD +exynos,CRTC,“mode”,ENUM,"{ ""normal"", ""blank"" }",CRTC,TBD +i2c/ch7006_drv,Generic,“scale”,RANGE,"Min=0, Max=2",Connector,TBD +,TV,“mode”,ENUM,"{ ""PAL"", ""PAL-M"",""PAL-N""}, ”PAL-Nc"" , ""PAL-60"", ""NTSC-M"", ""NTSC-J"" }",Connector,TBD +nouveau,NV10 Overlay,"""colorkey""",RANGE,"Min=0, Max=0x01ffffff",Plane,TBD +,,“contrast”,RANGE,"Min=0, Max=8192-1",Plane,TBD +,,“brightness”,RANGE,"Min=0, Max=1024",Plane,TBD +,,“hue”,RANGE,"Min=0, Max=359",Plane,TBD +,,“saturation”,RANGE,"Min=0, Max=8192-1",Plane,TBD +,,“iturbt_709”,RANGE,"Min=0, Max=1",Plane,TBD +,Nv04 Overlay,“colorkey”,RANGE,"Min=0, Max=0x01ffffff",Plane,TBD +,,“brightness”,RANGE,"Min=0, Max=1024",Plane,TBD +,Display,“dithering mode”,ENUM,"{ ""auto"", ""off"", ""on"" }",Connector,TBD +,,“dithering depth”,ENUM,"{ ""auto"", ""off"", ""on"", ""static 2x2"", ""dynamic 2x2"", ""temporal"" }",Connector,TBD +,,“underscan”,ENUM,"{ ""auto"", ""6 bpc"", ""8 bpc"" }",Connector,TBD +,,“underscan hborder”,RANGE,"Min=0, Max=128",Connector,TBD +,,“underscan vborder”,RANGE,"Min=0, Max=128",Connector,TBD +,,“vibrant hue”,RANGE,"Min=0, Max=180",Connector,TBD +,,“color vibrance”,RANGE,"Min=0, Max=200",Connector,TBD +omap,Generic,“zorder”,RANGE,"Min=0, Max=3","CRTC, Plane",TBD +qxl,Generic,"“hotplug_mode_update""",RANGE,"Min=0, Max=1",Connector,TBD +radeon,DVI-I,“coherent”,RANGE,"Min=0, Max=1",Connector,TBD +,DAC enable load detect,“load detection”,RANGE,"Min=0, Max=1",Connector,TBD +,TV Standard,"""tv standard""",ENUM,"{ ""ntsc"", ""pal"", ""pal-m"", ""pal-60"", ""ntsc-j"" , ""scart-pal"", ""pal-cn"", ""secam"" }",Connector,TBD +,legacy TMDS PLL detect,"""tmds_pll""",ENUM,"{ ""driver"", ""bios"" }",-,TBD +,Underscan,"""underscan""",ENUM,"{ ""off"", ""on"", ""auto"" }",Connector,TBD +,,"""underscan hborder""",RANGE,"Min=0, Max=128",Connector,TBD +,,"""underscan vborder""",RANGE,"Min=0, Max=128",Connector,TBD +,Audio,“audio”,ENUM,"{ ""off"", ""on"", ""auto"" }",Connector,TBD +,FMT Dithering,“dither”,ENUM,"{ ""off"", ""on"" }",Connector,TBD +,,"""colorkey""",RANGE,"Min=0, Max=0x01ffffff",Plane,TBD diff --git a/Documentation/gpu/komeda-kms.rst b/Documentation/gpu/komeda-kms.rst new file mode 100644 index 000000000..eb693c857 --- /dev/null +++ b/Documentation/gpu/komeda-kms.rst @@ -0,0 +1,488 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================== + drm/komeda Arm display driver +============================== + +The drm/komeda driver supports the Arm display processor D71 and later products, +this document gives a brief overview of driver design: how it works and why +design it like that. + +Overview of D71 like display IPs +================================ + +From D71, Arm display IP begins to adopt a flexible and modularized +architecture. A display pipeline is made up of multiple individual and +functional pipeline stages called components, and every component has some +specific capabilities that can give the flowed pipeline pixel data a +particular processing. + +Typical D71 components: + +Layer +----- +Layer is the first pipeline stage, which prepares the pixel data for the next +stage. It fetches the pixel from memory, decodes it if it's AFBC, rotates the +source image, unpacks or converts YUV pixels to the device internal RGB pixels, +then adjusts the color_space of pixels if needed. + +Scaler +------ +As its name suggests, scaler takes responsibility for scaling, and D71 also +supports image enhancements by scaler. +The usage of scaler is very flexible and can be connected to layer output +for layer scaling, or connected to compositor and scale the whole display +frame and then feed the output data into wb_layer which will then write it +into memory. + +Compositor (compiz) +------------------- +Compositor blends multiple layers or pixel data flows into one single display +frame. its output frame can be fed into post image processor for showing it on +the monitor or fed into wb_layer and written to memory at the same time. +user can also insert a scaler between compositor and wb_layer to down scale +the display frame first and then write to memory. + +Writeback Layer (wb_layer) +-------------------------- +Writeback layer does the opposite things of Layer, which connects to compiz +and writes the composition result to memory. + +Post image processor (improc) +----------------------------- +Post image processor adjusts frame data like gamma and color space to fit the +requirements of the monitor. + +Timing controller (timing_ctrlr) +-------------------------------- +Final stage of display pipeline, Timing controller is not for the pixel +handling, but only for controlling the display timing. + +Merger +------ +D71 scaler mostly only has the half horizontal input/output capabilities +compared with Layer, like if Layer supports 4K input size, the scaler only can +support 2K input/output in the same time. To achieve the ful frame scaling, D71 +introduces Layer Split, which splits the whole image to two half parts and feeds +them to two Layers A and B, and does the scaling independently. After scaling +the result need to be fed to merger to merge two part images together, and then +output merged result to compiz. + +Splitter +-------- +Similar to Layer Split, but Splitter is used for writeback, which splits the +compiz result to two parts and then feed them to two scalers. + +Possible D71 Pipeline usage +=========================== + +Benefitting from the modularized architecture, D71 pipelines can be easily +adjusted to fit different usages. And D71 has two pipelines, which support two +types of working mode: + +- Dual display mode + Two pipelines work independently and separately to drive two display outputs. + +- Single display mode + Two pipelines work together to drive only one display output. + + On this mode, pipeline_B doesn't work indenpendently, but outputs its + composition result into pipeline_A, and its pixel timing also derived from + pipeline_A.timing_ctrlr. The pipeline_B works just like a "slave" of + pipeline_A(master) + +Single pipeline data flow +------------------------- + +.. kernel-render:: DOT + :alt: Single pipeline digraph + :caption: Single pipeline data flow + + digraph single_ppl { + rankdir=LR; + + subgraph { + "Memory"; + "Monitor"; + } + + subgraph cluster_pipeline { + style=dashed + node [shape=box] + { + node [bgcolor=grey style=dashed] + "Scaler-0"; + "Scaler-1"; + "Scaler-0/1" + } + + node [bgcolor=grey style=filled] + "Layer-0" -> "Scaler-0" + "Layer-1" -> "Scaler-0" + "Layer-2" -> "Scaler-1" + "Layer-3" -> "Scaler-1" + + "Layer-0" -> "Compiz" + "Layer-1" -> "Compiz" + "Layer-2" -> "Compiz" + "Layer-3" -> "Compiz" + "Scaler-0" -> "Compiz" + "Scaler-1" -> "Compiz" + + "Compiz" -> "Scaler-0/1" -> "Wb_layer" + "Compiz" -> "Improc" -> "Timing Controller" + } + + "Wb_layer" -> "Memory" + "Timing Controller" -> "Monitor" + } + +Dual pipeline with Slave enabled +-------------------------------- + +.. kernel-render:: DOT + :alt: Slave pipeline digraph + :caption: Slave pipeline enabled data flow + + digraph slave_ppl { + rankdir=LR; + + subgraph { + "Memory"; + "Monitor"; + } + node [shape=box] + subgraph cluster_pipeline_slave { + style=dashed + label="Slave Pipeline_B" + node [shape=box] + { + node [bgcolor=grey style=dashed] + "Slave.Scaler-0"; + "Slave.Scaler-1"; + } + + node [bgcolor=grey style=filled] + "Slave.Layer-0" -> "Slave.Scaler-0" + "Slave.Layer-1" -> "Slave.Scaler-0" + "Slave.Layer-2" -> "Slave.Scaler-1" + "Slave.Layer-3" -> "Slave.Scaler-1" + + "Slave.Layer-0" -> "Slave.Compiz" + "Slave.Layer-1" -> "Slave.Compiz" + "Slave.Layer-2" -> "Slave.Compiz" + "Slave.Layer-3" -> "Slave.Compiz" + "Slave.Scaler-0" -> "Slave.Compiz" + "Slave.Scaler-1" -> "Slave.Compiz" + } + + subgraph cluster_pipeline_master { + style=dashed + label="Master Pipeline_A" + node [shape=box] + { + node [bgcolor=grey style=dashed] + "Scaler-0"; + "Scaler-1"; + "Scaler-0/1" + } + + node [bgcolor=grey style=filled] + "Layer-0" -> "Scaler-0" + "Layer-1" -> "Scaler-0" + "Layer-2" -> "Scaler-1" + "Layer-3" -> "Scaler-1" + + "Slave.Compiz" -> "Compiz" + "Layer-0" -> "Compiz" + "Layer-1" -> "Compiz" + "Layer-2" -> "Compiz" + "Layer-3" -> "Compiz" + "Scaler-0" -> "Compiz" + "Scaler-1" -> "Compiz" + + "Compiz" -> "Scaler-0/1" -> "Wb_layer" + "Compiz" -> "Improc" -> "Timing Controller" + } + + "Wb_layer" -> "Memory" + "Timing Controller" -> "Monitor" + } + +Sub-pipelines for input and output +---------------------------------- + +A complete display pipeline can be easily divided into three sub-pipelines +according to the in/out usage. + +Layer(input) pipeline +~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-render:: DOT + :alt: Layer data digraph + :caption: Layer (input) data flow + + digraph layer_data_flow { + rankdir=LR; + node [shape=box] + + { + node [bgcolor=grey style=dashed] + "Scaler-n"; + } + + "Layer-n" -> "Scaler-n" -> "Compiz" + } + +.. kernel-render:: DOT + :alt: Layer Split digraph + :caption: Layer Split pipeline + + digraph layer_data_flow { + rankdir=LR; + node [shape=box] + + "Layer-0/1" -> "Scaler-0" -> "Merger" + "Layer-2/3" -> "Scaler-1" -> "Merger" + "Merger" -> "Compiz" + } + +Writeback(output) pipeline +~~~~~~~~~~~~~~~~~~~~~~~~~~ +.. kernel-render:: DOT + :alt: writeback digraph + :caption: Writeback(output) data flow + + digraph writeback_data_flow { + rankdir=LR; + node [shape=box] + + { + node [bgcolor=grey style=dashed] + "Scaler-n"; + } + + "Compiz" -> "Scaler-n" -> "Wb_layer" + } + +.. kernel-render:: DOT + :alt: split writeback digraph + :caption: Writeback(output) Split data flow + + digraph writeback_data_flow { + rankdir=LR; + node [shape=box] + + "Compiz" -> "Splitter" + "Splitter" -> "Scaler-0" -> "Merger" + "Splitter" -> "Scaler-1" -> "Merger" + "Merger" -> "Wb_layer" + } + +Display output pipeline +~~~~~~~~~~~~~~~~~~~~~~~ +.. kernel-render:: DOT + :alt: display digraph + :caption: display output data flow + + digraph single_ppl { + rankdir=LR; + node [shape=box] + + "Compiz" -> "Improc" -> "Timing Controller" + } + +In the following section we'll see these three sub-pipelines will be handled +by KMS-plane/wb_conn/crtc respectively. + +Komeda Resource abstraction +=========================== + +struct komeda_pipeline/component +-------------------------------- + +To fully utilize and easily access/configure the HW, the driver side also uses +a similar architecture: Pipeline/Component to describe the HW features and +capabilities, and a specific component includes two parts: + +- Data flow controlling. +- Specific component capabilities and features. + +So the driver defines a common header struct komeda_component to describe the +data flow control and all specific components are a subclass of this base +structure. + +.. kernel-doc:: drivers/gpu/drm/arm/display/komeda/komeda_pipeline.h + :internal: + +Resource discovery and initialization +===================================== + +Pipeline and component are used to describe how to handle the pixel data. We +still need a @struct komeda_dev to describe the whole view of the device, and +the control-abilites of device. + +We have &komeda_dev, &komeda_pipeline, &komeda_component. Now fill devices with +pipelines. Since komeda is not for D71 only but also intended for later products, +of course we’d better share as much as possible between different products. To +achieve this, split the komeda device into two layers: CORE and CHIP. + +- CORE: for common features and capabilities handling. +- CHIP: for register programing and HW specific feature (limitation) handling. + +CORE can access CHIP by three chip function structures: + +- struct komeda_dev_funcs +- struct komeda_pipeline_funcs +- struct komeda_component_funcs + +.. kernel-doc:: drivers/gpu/drm/arm/display/komeda/komeda_dev.h + :internal: + +Format handling +=============== + +.. kernel-doc:: drivers/gpu/drm/arm/display/komeda/komeda_format_caps.h + :internal: +.. kernel-doc:: drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.h + :internal: + +Attach komeda_dev to DRM-KMS +============================ + +Komeda abstracts resources by pipeline/component, but DRM-KMS uses +crtc/plane/connector. One KMS-obj cannot represent only one single component, +since the requirements of a single KMS object cannot simply be achieved by a +single component, usually that needs multiple components to fit the requirement. +Like set mode, gamma, ctm for KMS all target on CRTC-obj, but komeda needs +compiz, improc and timing_ctrlr to work together to fit these requirements. +And a KMS-Plane may require multiple komeda resources: layer/scaler/compiz. + +So, one KMS-Obj represents a sub-pipeline of komeda resources. + +- Plane: `Layer(input) pipeline`_ +- Wb_connector: `Writeback(output) pipeline`_ +- Crtc: `Display output pipeline`_ + +So, for komeda, we treat KMS crtc/plane/connector as users of pipeline and +component, and at any one time a pipeline/component only can be used by one +user. And pipeline/component will be treated as private object of DRM-KMS; the +state will be managed by drm_atomic_state as well. + +How to map plane to Layer(input) pipeline +----------------------------------------- + +Komeda has multiple Layer input pipelines, see: +- `Single pipeline data flow`_ +- `Dual pipeline with Slave enabled`_ + +The easiest way is binding a plane to a fixed Layer pipeline, but consider the +komeda capabilities: + +- Layer Split, See `Layer(input) pipeline`_ + + Layer_Split is quite complicated feature, which splits a big image into two + parts and handles it by two layers and two scalers individually. But it + imports an edge problem or effect in the middle of the image after the split. + To avoid such a problem, it needs a complicated Split calculation and some + special configurations to the layer and scaler. We'd better hide such HW + related complexity to user mode. + +- Slave pipeline, See `Dual pipeline with Slave enabled`_ + + Since the compiz component doesn't output alpha value, the slave pipeline + only can be used for bottom layers composition. The komeda driver wants to + hide this limitation to the user. The way to do this is to pick a suitable + Layer according to plane_state->zpos. + +So for komeda, the KMS-plane doesn't represent a fixed komeda layer pipeline, +but multiple Layers with same capabilities. Komeda will select one or more +Layers to fit the requirement of one KMS-plane. + +Make component/pipeline to be drm_private_obj +--------------------------------------------- + +Add :c:type:`drm_private_obj` to :c:type:`komeda_component`, :c:type:`komeda_pipeline` + +.. code-block:: c + + struct komeda_component { + struct drm_private_obj obj; + ... + } + + struct komeda_pipeline { + struct drm_private_obj obj; + ... + } + +Tracking component_state/pipeline_state by drm_atomic_state +----------------------------------------------------------- + +Add :c:type:`drm_private_state` and user to :c:type:`komeda_component_state`, +:c:type:`komeda_pipeline_state` + +.. code-block:: c + + struct komeda_component_state { + struct drm_private_state obj; + void *binding_user; + ... + } + + struct komeda_pipeline_state { + struct drm_private_state obj; + struct drm_crtc *crtc; + ... + } + +komeda component validation +--------------------------- + +Komeda has multiple types of components, but the process of validation are +similar, usually including the following steps: + +.. code-block:: c + + int komeda_xxxx_validate(struct komeda_component_xxx xxx_comp, + struct komeda_component_output *input_dflow, + struct drm_plane/crtc/connector *user, + struct drm_plane/crtc/connector_state, *user_state) + { + setup 1: check if component is needed, like the scaler is optional depending + on the user_state; if unneeded, just return, and the caller will + put the data flow into next stage. + Setup 2: check user_state with component features and capabilities to see + if requirements can be met; if not, return fail. + Setup 3: get component_state from drm_atomic_state, and try set to set + user to component; fail if component has been assigned to another + user already. + Setup 3: configure the component_state, like set its input component, + convert user_state to component specific state. + Setup 4: adjust the input_dflow and prepare it for the next stage. + } + +komeda_kms Abstraction +---------------------- + +.. kernel-doc:: drivers/gpu/drm/arm/display/komeda/komeda_kms.h + :internal: + +komde_kms Functions +------------------- +.. kernel-doc:: drivers/gpu/drm/arm/display/komeda/komeda_crtc.c + :internal: +.. kernel-doc:: drivers/gpu/drm/arm/display/komeda/komeda_plane.c + :internal: + +Build komeda to be a Linux module driver +======================================== + +Now we have two level devices: + +- komeda_dev: describes the real display hardware. +- komeda_kms_dev: attachs or connects komeda_dev to DRM-KMS. + +All komeda operations are supplied or operated by komeda_dev or komeda_kms_dev, +the module driver is only a simple wrapper to pass the Linux command +(probe/remove/pm) into komeda_dev or komeda_kms_dev. diff --git a/Documentation/gpu/mcde.rst b/Documentation/gpu/mcde.rst new file mode 100644 index 000000000..dd43dde37 --- /dev/null +++ b/Documentation/gpu/mcde.rst @@ -0,0 +1,8 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================================================= + drm/mcde ST-Ericsson MCDE Multi-channel display engine +======================================================= + +.. kernel-doc:: drivers/gpu/drm/mcde/mcde_drv.c + :doc: ST-Ericsson MCDE Driver diff --git a/Documentation/gpu/meson.rst b/Documentation/gpu/meson.rst new file mode 100644 index 000000000..b9e2f9aa3 --- /dev/null +++ b/Documentation/gpu/meson.rst @@ -0,0 +1,55 @@ +============================================= +drm/meson AmLogic Meson Video Processing Unit +============================================= + +.. kernel-doc:: drivers/gpu/drm/meson/meson_drv.c + :doc: Video Processing Unit + +Video Processing Unit +===================== + +The Amlogic Meson Display controller is composed of several components +that are going to be documented below: + +.. code:: + + DMC|---------------VPU (Video Processing Unit)----------------|------HHI------| + | vd1 _______ _____________ _________________ | | + D |-------| |----| | | | | HDMI PLL | + D | vd2 | VIU | | Video Post | | Video Encoders |<---|-----VCLK | + R |-------| |----| Processing | | | | | + | osd2 | | | |---| Enci ----------|----|-----VDAC------| + R |-------| CSC |----| Scalers | | Encp ----------|----|----HDMI-TX----| + A | osd1 | | | Blenders | | Encl ----------|----|---------------| + M |-------|______|----|____________| |________________| | | + ___|__________________________________________________________|_______________| + +Video Input Unit +================ + +.. kernel-doc:: drivers/gpu/drm/meson/meson_viu.c + :doc: Video Input Unit + +Video Post Processing +===================== + +.. kernel-doc:: drivers/gpu/drm/meson/meson_vpp.c + :doc: Video Post Processing + +Video Encoder +============= + +.. kernel-doc:: drivers/gpu/drm/meson/meson_venc.c + :doc: Video Encoder + +Video Clocks +============ + +.. kernel-doc:: drivers/gpu/drm/meson/meson_vclk.c + :doc: Video Clocks + +HDMI Video Output +================= + +.. kernel-doc:: drivers/gpu/drm/meson/meson_dw_hdmi.c + :doc: HDMI Output diff --git a/Documentation/gpu/msm-crash-dump.rst b/Documentation/gpu/msm-crash-dump.rst new file mode 100644 index 000000000..240ef200f --- /dev/null +++ b/Documentation/gpu/msm-crash-dump.rst @@ -0,0 +1,98 @@ +:orphan: + +===================== +MSM Crash Dump Format +===================== + +Following a GPU hang the MSM driver outputs debugging information via +/sys/kernel/dri/X/show or via devcoredump (/sys/class/devcoredump/dcdX/data). +This document describes how the output is formatted. + +Each entry is in the form key: value. Sections headers will not have a value +and all the contents of a section will be indented two spaces from the header. +Each section might have multiple array entries the start of which is designated +by a (-). + +Mappings +-------- + +kernel + The kernel version that generated the dump (UTS_RELEASE). + +module + The module that generated the crashdump. + +time + The kernel time at crash formated as seconds.microseconds. + +comm + Comm string for the binary that generated the fault. + +cmdline + Command line for the binary that generated the fault. + +revision + ID of the GPU that generated the crash formatted as + core.major.minor.patchlevel separated by dots. + +rbbm-status + The current value of RBBM_STATUS which shows what top level GPU + components are in use at the time of crash. + +ringbuffer + Section containing the contents of each ringbuffer. Each ringbuffer is + identified with an id number. + + id + Ringbuffer ID (0 based index). Each ringbuffer in the section + will have its own unique id. + iova + GPU address of the ringbuffer. + + last-fence + The last fence that was issued on the ringbuffer + + retired-fence + The last fence retired on the ringbuffer. + + rptr + The current read pointer (rptr) for the ringbuffer. + + wptr + The current write pointer (wptr) for the ringbuffer. + + size + Maximum size of the ringbuffer programmed in the hardware. + + data + The contents of the ring encoded as ascii85. Only the used + portions of the ring will be printed. + +bo + List of buffers from the hanging submission if available. + Each buffer object will have a uinque iova. + + iova + GPU address of the buffer object. + + size + Allocated size of the buffer object. + + data + The contents of the buffer object encoded with ascii85. Only + Trailing zeros at the end of the buffer will be skipped. + +registers + Set of registers values. Each entry is on its own line enclosed + by brackets { }. + + offset + Byte offset of the register from the start of the + GPU memory region. + + value + Hexadecimal value of the register. + +registers-hlsq + (5xx only) Register values from the HLSQ aperture. + Same format as the register section. diff --git a/Documentation/gpu/pl111.rst b/Documentation/gpu/pl111.rst new file mode 100644 index 000000000..6d9a1b59a --- /dev/null +++ b/Documentation/gpu/pl111.rst @@ -0,0 +1,6 @@ +==================================================== + drm/pl111 ARM PrimeCell PL110 and PL111 CLCD Driver +==================================================== + +.. kernel-doc:: drivers/gpu/drm/pl111/pl111_drv.c + :doc: ARM PrimeCell PL110 and PL111 CLCD Driver diff --git a/Documentation/gpu/tegra.rst b/Documentation/gpu/tegra.rst new file mode 100644 index 000000000..d2ed8938c --- /dev/null +++ b/Documentation/gpu/tegra.rst @@ -0,0 +1,178 @@ +=============================================== + drm/tegra NVIDIA Tegra GPU and display driver +=============================================== + +NVIDIA Tegra SoCs support a set of display, graphics and video functions via +the host1x controller. host1x supplies command streams, gathered from a push +buffer provided directly by the CPU, to its clients via channels. Software, +or blocks amongst themselves, can use syncpoints for synchronization. + +Up until, but not including, Tegra124 (aka Tegra K1) the drm/tegra driver +supports the built-in GPU, comprised of the gr2d and gr3d engines. Starting +with Tegra124 the GPU is based on the NVIDIA desktop GPU architecture and +supported by the drm/nouveau driver. + +The drm/tegra driver supports NVIDIA Tegra SoC generations since Tegra20. It +has three parts: + + - A host1x driver that provides infrastructure and access to the host1x + services. + + - A KMS driver that supports the display controllers as well as a number of + outputs, such as RGB, HDMI, DSI, and DisplayPort. + + - A set of custom userspace IOCTLs that can be used to submit jobs to the + GPU and video engines via host1x. + +Driver Infrastructure +===================== + +The various host1x clients need to be bound together into a logical device in +order to expose their functionality to users. The infrastructure that supports +this is implemented in the host1x driver. When a driver is registered with the +infrastructure it provides a list of compatible strings specifying the devices +that it needs. The infrastructure creates a logical device and scan the device +tree for matching device nodes, adding the required clients to a list. Drivers +for individual clients register with the infrastructure as well and are added +to the logical host1x device. + +Once all clients are available, the infrastructure will initialize the logical +device using a driver-provided function which will set up the bits specific to +the subsystem and in turn initialize each of its clients. + +Similarly, when one of the clients is unregistered, the infrastructure will +destroy the logical device by calling back into the driver, which ensures that +the subsystem specific bits are torn down and the clients destroyed in turn. + +Host1x Infrastructure Reference +------------------------------- + +.. kernel-doc:: include/linux/host1x.h + +.. kernel-doc:: drivers/gpu/host1x/bus.c + :export: + +Host1x Syncpoint Reference +-------------------------- + +.. kernel-doc:: drivers/gpu/host1x/syncpt.c + :export: + +KMS driver +========== + +The display hardware has remained mostly backwards compatible over the various +Tegra SoC generations, up until Tegra186 which introduces several changes that +make it difficult to support with a parameterized driver. + +Display Controllers +------------------- + +Tegra SoCs have two display controllers, each of which can be associated with +zero or more outputs. Outputs can also share a single display controller, but +only if they run with compatible display timings. Two display controllers can +also share a single framebuffer, allowing cloned configurations even if modes +on two outputs don't match. A display controller is modelled as a CRTC in KMS +terms. + +On Tegra186, the number of display controllers has been increased to three. A +display controller can no longer drive all of the outputs. While two of these +controllers can drive both DSI outputs and both SOR outputs, the third cannot +drive any DSI. + +Windows +~~~~~~~ + +A display controller controls a set of windows that can be used to composite +multiple buffers onto the screen. While it is possible to assign arbitrary Z +ordering to individual windows (by programming the corresponding blending +registers), this is currently not supported by the driver. Instead, it will +assume a fixed Z ordering of the windows (window A is the root window, that +is, the lowest, while windows B and C are overlaid on top of window A). The +overlay windows support multiple pixel formats and can automatically convert +from YUV to RGB at scanout time. This makes them useful for displaying video +content. In KMS, each window is modelled as a plane. Each display controller +has a hardware cursor that is exposed as a cursor plane. + +Outputs +------- + +The type and number of supported outputs varies between Tegra SoC generations. +All generations support at least HDMI. While earlier generations supported the +very simple RGB interfaces (one per display controller), recent generations no +longer do and instead provide standard interfaces such as DSI and eDP/DP. + +Outputs are modelled as a composite encoder/connector pair. + +RGB/LVDS +~~~~~~~~ + +This interface is no longer available since Tegra124. It has been replaced by +the more standard DSI and eDP interfaces. + +HDMI +~~~~ + +HDMI is supported on all Tegra SoCs. Starting with Tegra210, HDMI is provided +by the versatile SOR output, which supports eDP, DP and HDMI. The SOR is able +to support HDMI 2.0, though support for this is currently not merged. + +DSI +~~~ + +Although Tegra has supported DSI since Tegra30, the controller has changed in +several ways in Tegra114. Since none of the publicly available development +boards prior to Dalmore (Tegra114) have made use of DSI, only Tegra114 and +later are supported by the drm/tegra driver. + +eDP/DP +~~~~~~ + +eDP was first introduced in Tegra124 where it was used to drive the display +panel for notebook form factors. Tegra210 added support for full DisplayPort +support, though this is currently not implemented in the drm/tegra driver. + +Userspace Interface +=================== + +The userspace interface provided by drm/tegra allows applications to create +GEM buffers, access and control syncpoints as well as submit command streams +to host1x. + +GEM Buffers +----------- + +The ``DRM_IOCTL_TEGRA_GEM_CREATE`` IOCTL is used to create a GEM buffer object +with Tegra-specific flags. This is useful for buffers that should be tiled, or +that are to be scanned out upside down (useful for 3D content). + +After a GEM buffer object has been created, its memory can be mapped by an +application using the mmap offset returned by the ``DRM_IOCTL_TEGRA_GEM_MMAP`` +IOCTL. + +Syncpoints +---------- + +The current value of a syncpoint can be obtained by executing the +``DRM_IOCTL_TEGRA_SYNCPT_READ`` IOCTL. Incrementing the syncpoint is achieved +using the ``DRM_IOCTL_TEGRA_SYNCPT_INCR`` IOCTL. + +Userspace can also request blocking on a syncpoint. To do so, it needs to +execute the ``DRM_IOCTL_TEGRA_SYNCPT_WAIT`` IOCTL, specifying the value of +the syncpoint to wait for. The kernel will release the application when the +syncpoint reaches that value or after a specified timeout. + +Command Stream Submission +------------------------- + +Before an application can submit command streams to host1x it needs to open a +channel to an engine using the ``DRM_IOCTL_TEGRA_OPEN_CHANNEL`` IOCTL. Client +IDs are used to identify the target of the channel. When a channel is no +longer needed, it can be closed using the ``DRM_IOCTL_TEGRA_CLOSE_CHANNEL`` +IOCTL. To retrieve the syncpoint associated with a channel, an application +can use the ``DRM_IOCTL_TEGRA_GET_SYNCPT``. + +After opening a channel, submitting command streams is easy. The application +writes commands into the memory backing a GEM buffer object and passes these +to the ``DRM_IOCTL_TEGRA_SUBMIT`` IOCTL along with various other parameters, +such as the syncpoints or relocations used in the job submission. diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst new file mode 100644 index 000000000..28841609a --- /dev/null +++ b/Documentation/gpu/todo.rst @@ -0,0 +1,677 @@ +.. _todo: + +========= +TODO list +========= + +This section contains a list of smaller janitorial tasks in the kernel DRM +graphics subsystem useful as newbie projects. Or for slow rainy days. + +Difficulty +---------- + +To make it easier task are categorized into different levels: + +Starter: Good tasks to get started with the DRM subsystem. + +Intermediate: Tasks which need some experience with working in the DRM +subsystem, or some specific GPU/display graphics knowledge. For debugging issue +it's good to have the relevant hardware (or a virtual driver set up) available +for testing. + +Advanced: Tricky tasks that need fairly good understanding of the DRM subsystem +and graphics topics. Generally need the relevant hardware for development and +testing. + +Subsystem-wide refactorings +=========================== + +Remove custom dumb_map_offset implementations +--------------------------------------------- + +All GEM based drivers should be using drm_gem_create_mmap_offset() instead. +Audit each individual driver, make sure it'll work with the generic +implementation (there's lots of outdated locking leftovers in various +implementations), and then remove it. + +Contact: Daniel Vetter, respective driver maintainers + +Level: Intermediate + +Convert existing KMS drivers to atomic modesetting +-------------------------------------------------- + +3.19 has the atomic modeset interfaces and helpers, so drivers can now be +converted over. Modern compositors like Wayland or Surfaceflinger on Android +really want an atomic modeset interface, so this is all about the bright +future. + +There is a conversion guide for atomic and all you need is a GPU for a +non-converted driver (again virtual HW drivers for KVM are still all +suitable). + +As part of this drivers also need to convert to universal plane (which means +exposing primary & cursor as proper plane objects). But that's much easier to +do by directly using the new atomic helper driver callbacks. + +Contact: Daniel Vetter, respective driver maintainers + +Level: Advanced + +Clean up the clipped coordination confusion around planes +--------------------------------------------------------- + +We have a helper to get this right with drm_plane_helper_check_update(), but +it's not consistently used. This should be fixed, preferrably in the atomic +helpers (and drivers then moved over to clipped coordinates). Probably the +helper should also be moved from drm_plane_helper.c to the atomic helpers, to +avoid confusion - the other helpers in that file are all deprecated legacy +helpers. + +Contact: Ville Syrjälä, Daniel Vetter, driver maintainers + +Level: Advanced + +Improve plane atomic_check helpers +---------------------------------- + +Aside from the clipped coordinates right above there's a few suboptimal things +with the current helpers: + +- drm_plane_helper_funcs->atomic_check gets called for enabled or disabled + planes. At best this seems to confuse drivers, worst it means they blow up + when the plane is disabled without the CRTC. The only special handling is + resetting values in the plane state structures, which instead should be moved + into the drm_plane_funcs->atomic_duplicate_state functions. + +- Once that's done, helpers could stop calling ->atomic_check for disabled + planes. + +- Then we could go through all the drivers and remove the more-or-less confused + checks for plane_state->fb and plane_state->crtc. + +Contact: Daniel Vetter + +Level: Advanced + +Convert early atomic drivers to async commit helpers +---------------------------------------------------- + +For the first year the atomic modeset helpers didn't support asynchronous / +nonblocking commits, and every driver had to hand-roll them. This is fixed +now, but there's still a pile of existing drivers that easily could be +converted over to the new infrastructure. + +One issue with the helpers is that they require that drivers handle completion +events for atomic commits correctly. But fixing these bugs is good anyway. + +Contact: Daniel Vetter, respective driver maintainers + +Level: Advanced + +Fallout from atomic KMS +----------------------- + +``drm_atomic_helper.c`` provides a batch of functions which implement legacy +IOCTLs on top of the new atomic driver interface. Which is really nice for +gradual conversion of drivers, but unfortunately the semantic mismatches are +a bit too severe. So there's some follow-up work to adjust the function +interfaces to fix these issues: + +* atomic needs the lock acquire context. At the moment that's passed around + implicitly with some horrible hacks, and it's also allocate with + ``GFP_NOFAIL`` behind the scenes. All legacy paths need to start allocating + the acquire context explicitly on stack and then also pass it down into + drivers explicitly so that the legacy-on-atomic functions can use them. + + Except for some driver code this is done. This task should be finished by + adding WARN_ON(!drm_drv_uses_atomic_modeset) in drm_modeset_lock_all(). + +* A bunch of the vtable hooks are now in the wrong place: DRM has a split + between core vfunc tables (named ``drm_foo_funcs``), which are used to + implement the userspace ABI. And then there's the optional hooks for the + helper libraries (name ``drm_foo_helper_funcs``), which are purely for + internal use. Some of these hooks should be move from ``_funcs`` to + ``_helper_funcs`` since they are not part of the core ABI. There's a + ``FIXME`` comment in the kerneldoc for each such case in ``drm_crtc.h``. + +Contact: Daniel Vetter + +Level: Intermediate + +Get rid of dev->struct_mutex from GEM drivers +--------------------------------------------- + +``dev->struct_mutex`` is the Big DRM Lock from legacy days and infested +everything. Nowadays in modern drivers the only bit where it's mandatory is +serializing GEM buffer object destruction. Which unfortunately means drivers +have to keep track of that lock and either call ``unreference`` or +``unreference_locked`` depending upon context. + +Core GEM doesn't have a need for ``struct_mutex`` any more since kernel 4.8, +and there's a ``gem_free_object_unlocked`` callback for any drivers which are +entirely ``struct_mutex`` free. + +For drivers that need ``struct_mutex`` it should be replaced with a driver- +private lock. The tricky part is the BO free functions, since those can't +reliably take that lock any more. Instead state needs to be protected with +suitable subordinate locks or some cleanup work pushed to a worker thread. For +performance-critical drivers it might also be better to go with a more +fine-grained per-buffer object and per-context lockings scheme. Currently only +the ``msm`` and `i915` drivers use ``struct_mutex``. + +Contact: Daniel Vetter, respective driver maintainers + +Level: Advanced + +Convert logging to drm_* functions with drm_device paramater +------------------------------------------------------------ + +For drivers which could have multiple instances, it is necessary to +differentiate between which is which in the logs. Since DRM_INFO/WARN/ERROR +don't do this, drivers used dev_info/warn/err to make this differentiation. We +now have drm_* variants of the drm print functions, so we can start to convert +those drivers back to using drm-formatted specific log messages. + +Before you start this conversion please contact the relevant maintainers to make +sure your work will be merged - not everyone agrees that the DRM dmesg macros +are better. + +Contact: Sean Paul, Maintainer of the driver you plan to convert + +Level: Starter + +Convert drivers to use simple modeset suspend/resume +---------------------------------------------------- + +Most drivers (except i915 and nouveau) that use +drm_atomic_helper_suspend/resume() can probably be converted to use +drm_mode_config_helper_suspend/resume(). Also there's still open-coded version +of the atomic suspend/resume code in older atomic modeset drivers. + +Contact: Maintainer of the driver you plan to convert + +Level: Intermediate + +Convert drivers to use drm_fbdev_generic_setup() +------------------------------------------------ + +Most drivers can use drm_fbdev_generic_setup(). Driver have to implement +atomic modesetting and GEM vmap support. Current generic fbdev emulation +expects the framebuffer in system memory (or system-like memory). + +Contact: Maintainer of the driver you plan to convert + +Level: Intermediate + +drm_framebuffer_funcs and drm_mode_config_funcs.fb_create cleanup +----------------------------------------------------------------- + +A lot more drivers could be switched over to the drm_gem_framebuffer helpers. +Various hold-ups: + +- Need to switch over to the generic dirty tracking code using + drm_atomic_helper_dirtyfb first (e.g. qxl). + +- Need to switch to drm_fbdev_generic_setup(), otherwise a lot of the custom fb + setup code can't be deleted. + +- Many drivers wrap drm_gem_fb_create() only to check for valid formats. For + atomic drivers we could check for valid formats by calling + drm_plane_check_pixel_format() against all planes, and pass if any plane + supports the format. For non-atomic that's not possible since like the format + list for the primary plane is fake and we'd therefor reject valid formats. + +- Many drivers subclass drm_framebuffer, we'd need a embedding compatible + version of the varios drm_gem_fb_create functions. Maybe called + drm_gem_fb_create/_with_dirty/_with_funcs as needed. + +Contact: Daniel Vetter + +Level: Intermediate + +Clean up mmap forwarding +------------------------ + +A lot of drivers forward gem mmap calls to dma-buf mmap for imported buffers. +And also a lot of them forward dma-buf mmap to the gem mmap implementations. +There's drm_gem_prime_mmap() for this now, but still needs to be rolled out. + +Contact: Daniel Vetter + +Level: Intermediate + +Generic fbdev defio support +--------------------------- + +The defio support code in the fbdev core has some very specific requirements, +which means drivers need to have a special framebuffer for fbdev. The main +issue is that it uses some fields in struct page itself, which breaks shmem +gem objects (and other things). To support defio, affected drivers require +the use of a shadow buffer, which may add CPU and memory overhead. + +Possible solution would be to write our own defio mmap code in the drm fbdev +emulation. It would need to fully wrap the existing mmap ops, forwarding +everything after it has done the write-protect/mkwrite trickery: + +- In the drm_fbdev_fb_mmap helper, if we need defio, change the + default page prots to write-protected with something like this:: + + vma->vm_page_prot = pgprot_wrprotect(vma->vm_page_prot); + +- Set the mkwrite and fsync callbacks with similar implementions to the core + fbdev defio stuff. These should all work on plain ptes, they don't actually + require a struct page. uff. These should all work on plain ptes, they don't + actually require a struct page. + +- Track the dirty pages in a separate structure (bitfield with one bit per page + should work) to avoid clobbering struct page. + +Might be good to also have some igt testcases for this. + +Contact: Daniel Vetter, Noralf Tronnes + +Level: Advanced + +idr_init_base() +--------------- + +DRM core&drivers uses a lot of idr (integer lookup directories) for mapping +userspace IDs to internal objects, and in most places ID=0 means NULL and hence +is never used. Switching to idr_init_base() for these would make the idr more +efficient. + +Contact: Daniel Vetter + +Level: Starter + +struct drm_gem_object_funcs +--------------------------- + +GEM objects can now have a function table instead of having the callbacks on the +DRM driver struct. This is now the preferred way and drivers can be moved over. + +We also need a 2nd version of the CMA define that doesn't require the +vmapping to be present (different hook for prime importing). Plus this needs to +be rolled out to all drivers using their own implementations, too. + +Level: Intermediate + +Use DRM_MODESET_LOCK_ALL_* helpers instead of boilerplate +--------------------------------------------------------- + +For cases where drivers are attempting to grab the modeset locks with a local +acquire context. Replace the boilerplate code surrounding +drm_modeset_lock_all_ctx() with DRM_MODESET_LOCK_ALL_BEGIN() and +DRM_MODESET_LOCK_ALL_END() instead. + +This should also be done for all places where drm_modeset_lock_all() is still +used. + +As a reference, take a look at the conversions already completed in drm core. + +Contact: Sean Paul, respective driver maintainers + +Level: Starter + +Rename CMA helpers to DMA helpers +--------------------------------- + +CMA (standing for contiguous memory allocator) is really a bit an accident of +what these were used for first, a much better name would be DMA helpers. In the +text these should even be called coherent DMA memory helpers (so maybe CDM, but +no one knows what that means) since underneath they just use dma_alloc_coherent. + +Contact: Laurent Pinchart, Daniel Vetter + +Level: Intermediate (mostly because it is a huge tasks without good partial +milestones, not technically itself that challenging) + +connector register/unregister fixes +----------------------------------- + +- For most connectors it's a no-op to call drm_connector_register/unregister + directly from driver code, drm_dev_register/unregister take care of this + already. We can remove all of them. + +- For dp drivers it's a bit more a mess, since we need the connector to be + registered when calling drm_dp_aux_register. Fix this by instead calling + drm_dp_aux_init, and moving the actual registering into a late_register + callback as recommended in the kerneldoc. + +Level: Intermediate + +Remove load/unload callbacks from all non-DRIVER_LEGACY drivers +--------------------------------------------------------------- + +The load/unload callbacks in struct &drm_driver are very much midlayers, plus +for historical reasons they get the ordering wrong (and we can't fix that) +between setting up the &drm_driver structure and calling drm_dev_register(). + +- Rework drivers to no longer use the load/unload callbacks, directly coding the + load/unload sequence into the driver's probe function. + +- Once all non-DRIVER_LEGACY drivers are converted, disallow the load/unload + callbacks for all modern drivers. + +Contact: Daniel Vetter + +Level: Intermediate + +Replace drm_detect_hdmi_monitor() with drm_display_info.is_hdmi +--------------------------------------------------------------- + +Once EDID is parsed, the monitor HDMI support information is available through +drm_display_info.is_hdmi. Many drivers still call drm_detect_hdmi_monitor() to +retrieve the same information, which is less efficient. + +Audit each individual driver calling drm_detect_hdmi_monitor() and switch to +drm_display_info.is_hdmi if applicable. + +Contact: Laurent Pinchart, respective driver maintainers + +Level: Intermediate + +Consolidate custom driver modeset properties +-------------------------------------------- + +Before atomic modeset took place, many drivers where creating their own +properties. Among other things, atomic brought the requirement that custom, +driver specific properties should not be used. + +For this task, we aim to introduce core helpers or reuse the existing ones +if available: + +A quick, unconfirmed, examples list. + +Introduce core helpers: +- audio (amdgpu, intel, gma500, radeon) +- brightness, contrast, etc (armada, nouveau) - overlay only (?) +- broadcast rgb (gma500, intel) +- colorkey (armada, nouveau, rcar) - overlay only (?) +- dither (amdgpu, nouveau, radeon) - varies across drivers +- underscan family (amdgpu, radeon, nouveau) + +Already in core: +- colorspace (sti) +- tv format names, enhancements (gma500, intel) +- tv overscan, margins, etc. (gma500, intel) +- zorder (omapdrm) - same as zpos (?) + + +Contact: Emil Velikov, respective driver maintainers + +Level: Intermediate + +Plumb drm_atomic_state all over +------------------------------- + +Currently various atomic functions take just a single or a handful of +object states (eg. plane state). While that single object state can +suffice for some simple cases, we often have to dig out additional +object states for dealing with various dependencies between the individual +objects or the hardware they represent. The process of digging out the +additional states is rather non-intuitive and error prone. + +To fix that most functions should rather take the overall +drm_atomic_state as one of their parameters. The other parameters +would generally be the object(s) we mainly want to interact with. + +For example, instead of + +.. code-block:: c + + int (*atomic_check)(struct drm_plane *plane, struct drm_plane_state *state); + +we would have something like + +.. code-block:: c + + int (*atomic_check)(struct drm_plane *plane, struct drm_atomic_state *state); + +The implementation can then trivially gain access to any required object +state(s) via drm_atomic_get_plane_state(), drm_atomic_get_new_plane_state(), +drm_atomic_get_old_plane_state(), and their equivalents for +other object types. + +Additionally many drivers currently access the object->state pointer +directly in their commit functions. That is not going to work if we +eg. want to allow deeper commit pipelines as those pointers could +then point to the states corresponding to a future commit instead of +the current commit we're trying to process. Also non-blocking commits +execute locklessly so there are serious concerns with dereferencing +the object->state pointers without holding the locks that protect them. +Use of drm_atomic_get_new_plane_state(), drm_atomic_get_old_plane_state(), +etc. avoids these problems as well since they relate to a specific +commit via the passed in drm_atomic_state. + +Contact: Ville Syrjälä, Daniel Vetter + +Level: Intermediate + + +Core refactorings +================= + +Make panic handling work +------------------------ + +This is a really varied tasks with lots of little bits and pieces: + +* The panic path can't be tested currently, leading to constant breaking. The + main issue here is that panics can be triggered from hardirq contexts and + hence all panic related callback can run in hardirq context. It would be + awesome if we could test at least the fbdev helper code and driver code by + e.g. trigger calls through drm debugfs files. hardirq context could be + achieved by using an IPI to the local processor. + +* There's a massive confusion of different panic handlers. DRM fbdev emulation + helpers have one, but on top of that the fbcon code itself also has one. We + need to make sure that they stop fighting over each another. + +* ``drm_can_sleep()`` is a mess. It hides real bugs in normal operations and + isn't a full solution for panic paths. We need to make sure that it only + returns true if there's a panic going on for real, and fix up all the + fallout. + +* The panic handler must never sleep, which also means it can't ever + ``mutex_lock()``. Also it can't grab any other lock unconditionally, not + even spinlocks (because NMI and hardirq can panic too). We need to either + make sure to not call such paths, or trylock everything. Really tricky. + +* For the above locking troubles reasons it's pretty much impossible to + attempt a synchronous modeset from panic handlers. The only thing we could + try to achive is an atomic ``set_base`` of the primary plane, and hope that + it shows up. Everything else probably needs to be delayed to some worker or + something else which happens later on. Otherwise it just kills the box + harder, prevent the panic from going out on e.g. netconsole. + +* There's also proposal for a simplied DRM console instead of the full-blown + fbcon and DRM fbdev emulation. Any kind of panic handling tricks should + obviously work for both console, in case we ever get kmslog merged. + +Contact: Daniel Vetter + +Level: Advanced + +Clean up the debugfs support +---------------------------- + +There's a bunch of issues with it: + +- The drm_info_list ->show() function doesn't even bother to cast to the drm + structure for you. This is lazy. + +- We probably want to have some support for debugfs files on crtc/connectors and + maybe other kms objects directly in core. There's even drm_print support in + the funcs for these objects to dump kms state, so it's all there. And then the + ->show() functions should obviously give you a pointer to the right object. + +- The drm_info_list stuff is centered on drm_minor instead of drm_device. For + anything we want to print drm_device (or maybe drm_file) is the right thing. + +- The drm_driver->debugfs_init hooks we have is just an artifact of the old + midlayered load sequence. DRM debugfs should work more like sysfs, where you + can create properties/files for an object anytime you want, and the core + takes care of publishing/unpuplishing all the files at register/unregister + time. Drivers shouldn't need to worry about these technicalities, and fixing + this (together with the drm_minor->drm_device move) would allow us to remove + debugfs_init. + +- Drop the return code and error checking from all debugfs functions. Greg KH is + working on this already. + +Contact: Daniel Vetter + +Level: Intermediate + +KMS cleanups +------------ + +Some of these date from the very introduction of KMS in 2008 ... + +- Make ->funcs and ->helper_private vtables optional. There's a bunch of empty + function tables in drivers, but before we can remove them we need to make sure + that all the users in helpers and drivers do correctly check for a NULL + vtable. + +- Cleanup up the various ->destroy callbacks. A lot of them just wrapt the + drm_*_cleanup implementations and can be removed. Some tack a kfree() at the + end, for which we could add drm_*_cleanup_kfree(). And then there's the (for + historical reasons) misnamed drm_primary_helper_destroy() function. + +Level: Intermediate + +Remove automatic page mapping from dma-buf importing +---------------------------------------------------- + +When importing dma-bufs, the dma-buf and PRIME frameworks automatically map +imported pages into the importer's DMA area. drm_gem_prime_fd_to_handle() and +drm_gem_prime_handle_to_fd() require that importers call dma_buf_attach() +even if they never do actual device DMA, but only CPU access through +dma_buf_vmap(). This is a problem for USB devices, which do not support DMA +operations. + +To fix the issue, automatic page mappings should be removed from the +buffer-sharing code. Fixing this is a bit more involved, since the import/export +cache is also tied to &drm_gem_object.import_attach. Meanwhile we paper over +this problem for USB devices by fishing out the USB host controller device, as +long as that supports DMA. Otherwise importing can still needlessly fail. + +Contact: Thomas Zimmermann <tzimmermann@suse.de>, Daniel Vetter + +Level: Advanced + + +Better Testing +============== + +Enable trinity for DRM +---------------------- + +And fix up the fallout. Should be really interesting ... + +Level: Advanced + +Make KMS tests in i-g-t generic +------------------------------- + +The i915 driver team maintains an extensive testsuite for the i915 DRM driver, +including tons of testcases for corner-cases in the modesetting API. It would +be awesome if those tests (at least the ones not relying on Intel-specific GEM +features) could be made to run on any KMS driver. + +Basic work to run i-g-t tests on non-i915 is done, what's now missing is mass- +converting things over. For modeset tests we also first need a bit of +infrastructure to use dumb buffers for untiled buffers, to be able to run all +the non-i915 specific modeset tests. + +Level: Advanced + +Extend virtual test driver (VKMS) +--------------------------------- + +See the documentation of :ref:`VKMS <vkms>` for more details. This is an ideal +internship task, since it only requires a virtual machine and can be sized to +fit the available time. + +Contact: Daniel Vetter + +Level: See details + +Backlight Refactoring +--------------------- + +Backlight drivers have a triple enable/disable state, which is a bit overkill. +Plan to fix this: + +1. Roll out backlight_enable() and backlight_disable() helpers everywhere. This + has started already. +2. In all, only look at one of the three status bits set by the above helpers. +3. Remove the other two status bits. + +Contact: Daniel Vetter + +Level: Intermediate + +Driver Specific +=============== + +AMD DC Display Driver +--------------------- + +AMD DC is the display driver for AMD devices starting with Vega. There has been +a bunch of progress cleaning it up but there's still plenty of work to be done. + +See drivers/gpu/drm/amd/display/TODO for tasks. + +Contact: Harry Wentland, Alex Deucher + +Bootsplash +========== + +There is support in place now for writing internal DRM clients making it +possible to pick up the bootsplash work that was rejected because it was written +for fbdev. + +- [v6,8/8] drm/client: Hack: Add bootsplash example + https://patchwork.freedesktop.org/patch/306579/ + +- [RFC PATCH v2 00/13] Kernel based bootsplash + https://lkml.org/lkml/2017/12/13/764 + +Contact: Sam Ravnborg + +Level: Advanced + +Outside DRM +=========== + +Convert fbdev drivers to DRM +---------------------------- + +There are plenty of fbdev drivers for older hardware. Some hwardware has +become obsolete, but some still provides good(-enough) framebuffers. The +drivers that are still useful should be converted to DRM and afterwards +removed from fbdev. + +Very simple fbdev drivers can best be converted by starting with a new +DRM driver. Simple KMS helpers and SHMEM should be able to handle any +existing hardware. The new driver's call-back functions are filled from +existing fbdev code. + +More complex fbdev drivers can be refactored step-by-step into a DRM +driver with the help of the DRM fbconv helpers. [1] These helpers provide +the transition layer between the DRM core infrastructure and the fbdev +driver interface. Create a new DRM driver on top of the fbconv helpers, +copy over the fbdev driver, and hook it up to the DRM code. Examples for +several fbdev drivers are available at [1] and a tutorial of this process +available at [2]. The result is a primitive DRM driver that can run X11 +and Weston. + + - [1] https://gitlab.freedesktop.org/tzimmermann/linux/tree/fbconv + - [2] https://gitlab.freedesktop.org/tzimmermann/linux/blob/fbconv/drivers/gpu/drm/drm_fbconv_helper.c + +Contact: Thomas Zimmermann <tzimmermann@suse.de> + +Level: Advanced diff --git a/Documentation/gpu/tve200.rst b/Documentation/gpu/tve200.rst new file mode 100644 index 000000000..152ea9398 --- /dev/null +++ b/Documentation/gpu/tve200.rst @@ -0,0 +1,6 @@ +================================== + drm/tve200 Faraday TV Encoder 200 +================================== + +.. kernel-doc:: drivers/gpu/drm/tve200/tve200_drv.c + :doc: Faraday TV Encoder TVE200 DRM Driver diff --git a/Documentation/gpu/v3d.rst b/Documentation/gpu/v3d.rst new file mode 100644 index 000000000..543f7fbf5 --- /dev/null +++ b/Documentation/gpu/v3d.rst @@ -0,0 +1,28 @@ +===================================== + drm/v3d Broadcom V3D Graphics Driver +===================================== + +.. kernel-doc:: drivers/gpu/drm/v3d/v3d_drv.c + :doc: Broadcom V3D Graphics Driver + +GPU buffer object (BO) management +--------------------------------- + +.. kernel-doc:: drivers/gpu/drm/v3d/v3d_bo.c + :doc: V3D GEM BO management support + +Address space management +=========================================== +.. kernel-doc:: drivers/gpu/drm/v3d/v3d_mmu.c + :doc: Broadcom V3D MMU + +GPU Scheduling +=========================================== +.. kernel-doc:: drivers/gpu/drm/v3d/v3d_sched.c + :doc: Broadcom V3D scheduling + +Interrupts +-------------- + +.. kernel-doc:: drivers/gpu/drm/v3d/v3d_irq.c + :doc: Interrupt management for the V3D engine diff --git a/Documentation/gpu/vc4.rst b/Documentation/gpu/vc4.rst new file mode 100644 index 000000000..5df1d98b9 --- /dev/null +++ b/Documentation/gpu/vc4.rst @@ -0,0 +1,89 @@ +===================================== + drm/vc4 Broadcom VC4 Graphics Driver +===================================== + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_drv.c + :doc: Broadcom VC4 Graphics Driver + +Display Hardware Handling +========================= + +This section covers everything related to the display hardware including +the mode setting infrastructure, plane, sprite and cursor handling and +display, output probing and related topics. + +Pixel Valve (DRM CRTC) +---------------------- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_crtc.c + :doc: VC4 CRTC module + +HVS +--- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_hvs.c + :doc: VC4 HVS module. + +HVS planes +---------- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_plane.c + :doc: VC4 plane module + +HDMI encoder +------------ + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_hdmi.c + :doc: VC4 Falcon HDMI module + +DSI encoder +----------- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_dsi.c + :doc: VC4 DSI0/DSI1 module + +DPI encoder +----------- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_dpi.c + :doc: VC4 DPI module + +VEC (Composite TV out) encoder +------------------------------ + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_vec.c + :doc: VC4 SDTV module + +Memory Management and 3D Command Submission +=========================================== + +This section covers the GEM implementation in the vc4 driver. + +GPU buffer object (BO) management +--------------------------------- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_bo.c + :doc: VC4 GEM BO management support + +V3D binner command list (BCL) validation +---------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_validate.c + :doc: Command list validator for VC4. + +V3D render command list (RCL) generation +---------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_render_cl.c + :doc: Render command list generation + +Shader validator for VC4 +--------------------------- +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_validate_shaders.c + :doc: Shader validator for VC4. + +V3D Interrupts +-------------- + +.. kernel-doc:: drivers/gpu/drm/vc4/vc4_irq.c + :doc: Interrupt management for the V3D engine diff --git a/Documentation/gpu/vga-switcheroo.rst b/Documentation/gpu/vga-switcheroo.rst new file mode 100644 index 000000000..cbbdb994f --- /dev/null +++ b/Documentation/gpu/vga-switcheroo.rst @@ -0,0 +1,98 @@ +.. _vga_switcheroo: + +============== +VGA Switcheroo +============== + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :doc: Overview + +Modes of Use +============ + +Manual switching and manual power control +----------------------------------------- + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :doc: Manual switching and manual power control + +Driver power control +-------------------- + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :doc: Driver power control + +API +=== + +Public functions +---------------- + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :export: + +Public structures +----------------- + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_handler + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_client_ops + +Public constants +---------------- + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_handler_flags_t + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_client_id + +.. kernel-doc:: include/linux/vga_switcheroo.h + :functions: vga_switcheroo_state + +Private structures +------------------ + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :functions: vgasr_priv + +.. kernel-doc:: drivers/gpu/vga/vga_switcheroo.c + :functions: vga_switcheroo_client + +Handlers +======== + +apple-gmux Handler +------------------ + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Overview + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Interrupt + +Graphics mux +~~~~~~~~~~~~ + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Graphics mux + +Power control +~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Power control + +Backlight control +~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/platform/x86/apple-gmux.c + :doc: Backlight control + +Public functions +~~~~~~~~~~~~~~~~ + +.. kernel-doc:: include/linux/apple-gmux.h + :internal: diff --git a/Documentation/gpu/vgaarbiter.rst b/Documentation/gpu/vgaarbiter.rst new file mode 100644 index 000000000..339ed5fec --- /dev/null +++ b/Documentation/gpu/vgaarbiter.rst @@ -0,0 +1,191 @@ +=========== +VGA Arbiter +=========== + +Graphic devices are accessed through ranges in I/O or memory space. While most +modern devices allow relocation of such ranges, some "Legacy" VGA devices +implemented on PCI will typically have the same "hard-decoded" addresses as +they did on ISA. For more details see "PCI Bus Binding to IEEE Std 1275-1994 +Standard for Boot (Initialization Configuration) Firmware Revision 2.1" +Section 7, Legacy Devices. + +The Resource Access Control (RAC) module inside the X server [0] existed for +the legacy VGA arbitration task (besides other bus management tasks) when more +than one legacy device co-exists on the same machine. But the problem happens +when these devices are trying to be accessed by different userspace clients +(e.g. two server in parallel). Their address assignments conflict. Moreover, +ideally, being a userspace application, it is not the role of the X server to +control bus resources. Therefore an arbitration scheme outside of the X server +is needed to control the sharing of these resources. This document introduces +the operation of the VGA arbiter implemented for the Linux kernel. + +vgaarb kernel/userspace ABI +--------------------------- + +The vgaarb is a module of the Linux Kernel. When it is initially loaded, it +scans all PCI devices and adds the VGA ones inside the arbitration. The +arbiter then enables/disables the decoding on different devices of the VGA +legacy instructions. Devices which do not want/need to use the arbiter may +explicitly tell it by calling vga_set_legacy_decoding(). + +The kernel exports a char device interface (/dev/vga_arbiter) to the clients, +which has the following semantics: + +open + Opens a user instance of the arbiter. By default, it's attached to the + default VGA device of the system. + +close + Close a user instance. Release locks made by the user + +read + Return a string indicating the status of the target like: + + "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)" + + An IO state string is of the form {io,mem,io+mem,none}, mc and + ic are respectively mem and io lock counts (for debugging/ + diagnostic only). "decodes" indicate what the card currently + decodes, "owns" indicates what is currently enabled on it, and + "locks" indicates what is locked by this card. If the card is + unplugged, we get "invalid" then for card_ID and an -ENODEV + error is returned for any command until a new card is targeted. + + +write + Write a command to the arbiter. List of commands: + + target <card_ID> + switch target to card <card_ID> (see below) + lock <io_state> + acquires locks on target ("none" is an invalid io_state) + trylock <io_state> + non-blocking acquire locks on target (returns EBUSY if + unsuccessful) + unlock <io_state> + release locks on target + unlock all + release all locks on target held by this user (not implemented + yet) + decodes <io_state> + set the legacy decoding attributes for the card + + poll + event if something changes on any card (not just the target) + + card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default" + to go back to the system default card (TODO: not implemented yet). Currently, + only PCI is supported as a prefix, but the userland API may support other bus + types in the future, even if the current kernel implementation doesn't. + +Note about locks: + +The driver keeps track of which user has which locks on which card. It +supports stacking, like the kernel one. This complexifies the implementation +a bit, but makes the arbiter more tolerant to user space problems and able +to properly cleanup in all cases when a process dies. +Currently, a max of 16 cards can have locks simultaneously issued from +user space for a given user (file descriptor instance) of the arbiter. + +In the case of devices hot-{un,}plugged, there is a hook - pci_notify() - to +notify them being added/removed in the system and automatically added/removed +in the arbiter. + +There is also an in-kernel API of the arbiter in case DRM, vgacon, or other +drivers want to use it. + +In-kernel interface +------------------- + +.. kernel-doc:: include/linux/vgaarb.h + :internal: + +.. kernel-doc:: drivers/gpu/vga/vgaarb.c + :export: + +libpciaccess +------------ + +To use the vga arbiter char device it was implemented an API inside the +libpciaccess library. One field was added to struct pci_device (each device +on the system):: + + /* the type of resource decoded by the device */ + int vgaarb_rsrc; + +Besides it, in pci_system were added:: + + int vgaarb_fd; + int vga_count; + struct pci_device *vga_target; + struct pci_device *vga_default_dev; + +The vga_count is used to track how many cards are being arbitrated, so for +instance, if there is only one card, then it can completely escape arbitration. + +These functions below acquire VGA resources for the given card and mark those +resources as locked. If the resources requested are "normal" (and not legacy) +resources, the arbiter will first check whether the card is doing legacy +decoding for that type of resource. If yes, the lock is "converted" into a +legacy resource lock. The arbiter will first look for all VGA cards that +might conflict and disable their IOs and/or Memory access, including VGA +forwarding on P2P bridges if necessary, so that the requested resources can +be used. Then, the card is marked as locking these resources and the IO and/or +Memory access is enabled on the card (including VGA forwarding on parent +P2P bridges if any). In the case of vga_arb_lock(), the function will block +if some conflicting card is already locking one of the required resources (or +any resource on a different bus segment, since P2P bridges don't differentiate +VGA memory and IO afaik). If the card already owns the resources, the function +succeeds. vga_arb_trylock() will return (-EBUSY) instead of blocking. Nested +calls are supported (a per-resource counter is maintained). + +Set the target device of this client. :: + + int pci_device_vgaarb_set_target (struct pci_device *dev); + +For instance, in x86 if two devices on the same bus want to lock different +resources, both will succeed (lock). If devices are in different buses and +trying to lock different resources, only the first who tried succeeds. :: + + int pci_device_vgaarb_lock (void); + int pci_device_vgaarb_trylock (void); + +Unlock resources of device. :: + + int pci_device_vgaarb_unlock (void); + +Indicates to the arbiter if the card decodes legacy VGA IOs, legacy VGA +Memory, both, or none. All cards default to both, the card driver (fbdev for +example) should tell the arbiter if it has disabled legacy decoding, so the +card can be left out of the arbitration process (and can be safe to take +interrupts at any time. :: + + int pci_device_vgaarb_decodes (int new_vgaarb_rsrc); + +Connects to the arbiter device, allocates the struct :: + + int pci_device_vgaarb_init (void); + +Close the connection :: + + void pci_device_vgaarb_fini (void); + +xf86VGAArbiter (X server implementation) +---------------------------------------- + +X server basically wraps all the functions that touch VGA registers somehow. + +References +---------- + +Benjamin Herrenschmidt (IBM?) started this work when he discussed such design +with the Xorg community in 2005 [1, 2]. In the end of 2007, Paulo Zanoni and +Tiago Vignatti (both of C3SL/Federal University of Paraná) proceeded his work +enhancing the kernel code to adapt as a kernel module and also did the +implementation of the user space side [3]. Now (2009) Tiago Vignatti and Dave +Airlie finally put this work in shape and queued to Jesse Barnes' PCI tree. + +0) https://cgit.freedesktop.org/xorg/xserver/commit/?id=4b42448a2388d40f257774fbffdccaea87bd0347 +1) https://lists.freedesktop.org/archives/xorg/2005-March/006663.html +2) https://lists.freedesktop.org/archives/xorg/2005-March/006745.html +3) https://lists.freedesktop.org/archives/xorg/2007-October/029507.html diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst new file mode 100644 index 000000000..61586fc86 --- /dev/null +++ b/Documentation/gpu/vkms.rst @@ -0,0 +1,110 @@ +.. _vkms: + +========================================== + drm/vkms Virtual Kernel Modesetting +========================================== + +.. kernel-doc:: drivers/gpu/drm/vkms/vkms_drv.c + :doc: vkms (Virtual Kernel Modesetting) + +TODO +==== + +CRC API Improvements +-------------------- + +- Optimize CRC computation ``compute_crc()`` and plane blending ``blend()`` + +- Use the alpha value to blend vaddr_src with vaddr_dst instead of + overwriting it in ``blend()``. + +- Add igt test to check cleared alpha value for XRGB plane format. + +- Add igt test to check extreme alpha values i.e. fully opaque and fully + transparent (intermediate values are affected by hw-specific rounding modes). + +Runtime Configuration +--------------------- + +We want to be able to reconfigure vkms instance without having to reload the +module. Use/Test-cases: + +- Hotplug/hotremove connectors on the fly (to be able to test DP MST handling of + compositors). + +- Configure planes/crtcs/connectors (we'd need some code to have more than 1 of + them first). + +- Change output configuration: Plug/unplug screens, change EDID, allow changing + the refresh rate. + +The currently proposed solution is to expose vkms configuration through +configfs. All existing module options should be supported through configfs too. + +Add Plane Features +------------------ + +There's lots of plane features we could add support for: + +- Real overlay planes, not just cursor. + +- Full alpha blending on all planes. + +- Rotation, scaling. + +- Additional buffer formats, especially YUV formats for video like NV12. + Low/high bpp RGB formats would also be interesting. + +- Async updates (currently only possible on cursor plane using the legacy cursor + api). + +For all of these, we also want to review the igt test coverage and make sure all +relevant igt testcases work on vkms. + +Writeback support +----------------- + +Currently vkms only computes a CRC for each frame. Once we have additional plane +features, we could write back the entire composited frame, and expose it as: + +- Writeback connector. This is useful for testing compositors if you don't have + hardware with writeback support. + +- As a v4l device. This is useful for debugging compositors on special vkms + configurations, so that developers see what's really going on. + +Prime Buffer Sharing +-------------------- + +We already have vgem, which is a gem driver for testing rendering, similar to +how vkms is for testing the modeset side. Adding buffer sharing support to vkms +allows us to test them together, to test synchronization and lots of other +features. Also, this allows compositors to test whether they work correctly on +SoC chips, where the display and rendering is very often split between 2 +drivers. + +Output Features +--------------- + +- Variable refresh rate/freesync support. This probably needs prime buffer + sharing support, so that we can use vgem fences to simulate rendering in + testing. Also needs support to specify the EDID. + +- Add support for link status, so that compositors can validate their runtime + fallbacks when e.g. a Display Port link goes bad. + +- All the hotplug handling describe under "Runtime Configuration". + +Atomic Check using eBPF +----------------------- + +Atomic drivers have lots of restrictions which are not exposed to userspace in +any explicit form through e.g. possible property values. Userspace can only +inquiry about these limits through the atomic IOCTL, possibly using the +TEST_ONLY flag. Trying to add configurable code for all these limits, to allow +compositors to be tested against them, would be rather futile exercise. Instead +we could add support for eBPF to validate any kind of atomic state, and +implement a library of different restrictions. + +This needs a bunch of features (plane compositing, multiple outputs, ...) +enabled already to make sense. diff --git a/Documentation/gpu/xen-front.rst b/Documentation/gpu/xen-front.rst new file mode 100644 index 000000000..d988da7d1 --- /dev/null +++ b/Documentation/gpu/xen-front.rst @@ -0,0 +1,31 @@ +==================================================== + drm/xen-front Xen para-virtualized frontend driver +==================================================== + +This frontend driver implements Xen para-virtualized display +according to the display protocol described at +include/xen/interface/io/displif.h + +Driver modes of operation in terms of display buffers used +========================================================== + +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h + :doc: Driver modes of operation in terms of display buffers used + +Buffers allocated by the frontend driver +---------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h + :doc: Buffers allocated by the frontend driver + +Buffers allocated by the backend +-------------------------------- + +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h + :doc: Buffers allocated by the backend + +Driver limitations +================== + +.. kernel-doc:: drivers/gpu/drm/xen/xen_drm_front.h + :doc: Driver limitations |