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diff --git a/Documentation/admin-guide/media/davinci-vpbe.rst b/Documentation/admin-guide/media/davinci-vpbe.rst new file mode 100644 index 000000000..9e6360fd0 --- /dev/null +++ b/Documentation/admin-guide/media/davinci-vpbe.rst @@ -0,0 +1,65 @@ +.. SPDX-License-Identifier: GPL-2.0 + +The VPBE V4L2 driver design +=========================== + +Functional partitioning +----------------------- + +Consists of the following: + + 1. V4L2 display driver + + Implements creation of video2 and video3 device nodes and + provides v4l2 device interface to manage VID0 and VID1 layers. + + 2. Display controller + + Loads up VENC, OSD and external encoders such as ths8200. It provides + a set of API calls to V4L2 drivers to set the output/standards + in the VENC or external sub devices. It also provides + a device object to access the services from OSD subdevice + using sub device ops. The connection of external encoders to VENC LCD + controller port is done at init time based on default output and standard + selection or at run time when application change the output through + V4L2 IOCTLs. + + When connected to an external encoder, vpbe controller is also responsible + for setting up the interface between VENC and external encoders based on + board specific settings (specified in board-xxx-evm.c). This allows + interfacing external encoders such as ths8200. The setup_if_config() + is implemented for this as well as configure_venc() (part of the next patch) + API to set timings in VENC for a specific display resolution. As of this + patch series, the interconnection and enabling and setting of the external + encoders is not present, and would be a part of the next patch series. + + 3. VENC subdevice module + + Responsible for setting outputs provided through internal DACs and also + setting timings at LCD controller port when external encoders are connected + at the port or LCD panel timings required. When external encoder/LCD panel + is connected, the timings for a specific standard/preset is retrieved from + the board specific table and the values are used to set the timings in + venc using non-standard timing mode. + + Support LCD Panel displays using the VENC. For example to support a Logic + PD display, it requires setting up the LCD controller port with a set of + timings for the resolution supported and setting the dot clock. So we could + add the available outputs as a board specific entry (i.e add the "LogicPD" + output name to board-xxx-evm.c). A table of timings for various LCDs + supported can be maintained in the board specific setup file to support + various LCD displays.As of this patch a basic driver is present, and this + support for external encoders and displays forms a part of the next + patch series. + + 4. OSD module + + OSD module implements all OSD layer management and hardware specific + features. The VPBE module interacts with the OSD for enabling and + disabling appropriate features of the OSD. + +Current status +-------------- + +A fully functional working version of the V4L2 driver is available. This +driver has been tested with NTSC and PAL standards and buffer streaming. |