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