66 lines
2.9 KiB
ReStructuredText
66 lines
2.9 KiB
ReStructuredText
|
.. 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.
|