Hi Hans,
I have another doubt regarding the framework choice for the entire system that I have, especially the video part of the system. The
overall
system is similar to the one depicted below:
HDMI data --> HDMI receiver chip --> Video Port IP on SoC --> System
DDR
HDMI data is received from external world (from say a set-up box or
dvd player),
which is fed to the HDMI receiver chip on-board and then parallel
data lines feed
this data to a Video Port IP on the SoC which has a DMA master
interface and
hence can push the data thus received directly on system DDR.
Now, I can figure out that there will be two drivers required here: # HDMI receiver chip driver (which is essentially a v4l2 subdev being
controller via I2C)
# Video Port driver (which is a v4l2 bridge driver)
Is my understanding correct?
Yes.
Thanks for clarifying this.
Are there any HDMI receiver subdev driver and video bridge driver
already available which I can
use for reference?
Video bridge drivers are easier: examples are in drivers/media/video/s5p-fimc or in drivers/media/video/davinci. Note that you should use the new videobuf2 framework instead of the older videobuf framework. s5p-fimc is using vb2 already. but the vpif capture and display drivers in the davinci directory do not.
I quickly had a look at the s5p-fimc and davinci approaches, but I found that the video bridge drivers supported in both the Samsung and TI SoCs, support video post-processing operations whereas in our case the Video Port IP performs almost no additional processing and only passes the unpacked RBG raw data received from HDMI bus to system DDR via a DMA master interface.
This is similar to the davinci vpif-capture/vpif-display drivers for the TI dm646x SoCs. Those videoports are also just a DMA engine without video processing.
So as such these are no format conversion operations(rgb-to-yuv or vice-versa), image resizing operations (cropping, scaling..) and image quality operations (filtering, distortion removal) available in the H/W block.
What should be the correct choice in such a case?
vpif-capture/display drivers are identical in that respect.
Regards,
Hans