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diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst new file mode 100644 index 0000000000..378e825754 --- /dev/null +++ b/Documentation/gpu/i915.rst @@ -0,0 +1,739 @@ +=========================== + 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: + +Asynchronous Page Flip +---------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_display.c + :doc: asynchronous flip implementation + +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_drrs.c + :doc: Display Refresh Rate Switching (DRRS) + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_drrs.c + :internal: + +DPIO +---- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpio_phy.c + :doc: DPIO + +DMC Firmware Support +-------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dmc.c + :doc: DMC Firmware Support + +.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dmc.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: + +GT Programming +============== + +Multicast/Replicated (MCR) Registers +------------------------------------ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_gt_mcr.c + :doc: GT Multicast/Replicated (MCR) Register Support + +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_gt_mcr.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 at least) 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 at least) 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_context_types.h + +.. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c + :doc: User command execution + +Scheduling +---------- +.. kernel-doc:: drivers/gpu/drm/i915/i915_scheduler_types.h + :functions: i915_sched_engine + +Logical Rings, Logical Ring Contexts and Execlists +-------------------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_execlists_submission.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 + +Protected Objects +----------------- + +.. kernel-doc:: drivers/gpu/drm/i915/pxp/intel_pxp.c + :doc: PXP + +.. kernel-doc:: drivers/gpu/drm/i915/pxp/intel_pxp_types.h + +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/gt/intel_wopcm.c + :doc: WOPCM Layout + +GuC +--- + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.c + :doc: GuC + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/intel_guc.h + +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 + +GuC ABI +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_messages_abi.h +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_communication_mmio_abi.h +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h +.. kernel-doc:: drivers/gpu/drm/i915/gt/uc/abi/guc_klvs_abi.h + +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 `DMC Firmware Support`_ + +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 + +.. _i915-usage-stats: + +i915 DRM client usage stats implementation +========================================== + +The drm/i915 driver implements the DRM client usage stats specification as +documented in :ref:`drm-client-usage-stats`. + +Example of the output showing the implemented key value pairs and entirety of +the currently possible format options: + +:: + + pos: 0 + flags: 0100002 + mnt_id: 21 + drm-driver: i915 + drm-pdev: 0000:00:02.0 + drm-client-id: 7 + drm-engine-render: 9288864723 ns + drm-engine-copy: 2035071108 ns + drm-engine-video: 0 ns + drm-engine-capacity-video: 2 + drm-engine-video-enhance: 0 ns + +Possible `drm-engine-` key names are: `render`, `copy`, `video` and +`video-enhance`. |