petatester

@Myy The patches I have in my rockchip-5.x-vpu branch is on top of v5.0-rc6 + mmind/for-next and not a rockchip tree.
 
All vpu related patches needed on top of v5.0-rc6: https://github.com/Kwiboo/linux-rockchip/compare/v5.0-rc6...rockchip-5.x-vpu (patch)
List of mmind/for-next patches rebased on v5.0-rc6: https://github.com/Kwiboo/linux-rockchip/compare/v5.0-rc6...rockchip-5.x (patch)
VPU related patches on top of mmind/for-next: https://github.com/Kwiboo/linux-rockchip/compare/rockchip-5.x...rockchip-5.x-vpu (patch)
 
I have started to send some of my patches to linux mailing list and more will follow.

Alright, the module not loading was due to one my patch modifying the DTSI in order to adapt to Ayaka driver, which used names like "VEPU" and "VDPU". So I basically copied back the nodes as they're defined in the rk3288.dtsi of your kernel tree.

So the module loads, media-test is able to list all the rockchip-vpu outputs (sink, ...). However this one, https://github.com/bootlin/v4l2-request-test , throws Invalid argument when trying to execute a VIDIOC_TRY_FMT . Given how IOCTL work, trying to recompile FFMPEG appears to be a "quicker" solution than debugging the tester from bootlin.

Is there a "quick" tester that just tries to decode ONE frame of a specific format, that is up to date and works with the currently implemented V4L2 Request extension ?

Well, while this is called a "Video Processing Unit", the thing is : there's a LOT of video file formats out there. Which mean, a lot of different parameters and decoding/decompressing methods, based on the format used. (I mean, there are different formats and there are "different" for a reason...)
All the VPU I know are specialized in decoding a few formats, at most : H264, H265, VP8, VP9, ...
 
For each format, the VPU must be configured to access external data like : The current frame, the configuration of the current stream (Width, Height, Bytes per pixel, Color format, ...), the different decoding tables if any (e.g. CABAC tables for H26x), ... .
The amount of external data and configuration vary from format to format, knowing that some formats can also have "sub-formats" (H264 is a good example of this madness) which require more or less parameters.
 
So, yeah, VPU are dedicated to a few formats, and for each format, the setup can be completely different. That can be due to configuration registers being mapped at different addresses depending on the decoded format, or the same registers having completely different meaning depending on the format decoded.
 
Note that, in this case, the VPU decode one frame per one frame.
You cannot just "Send the MKV to the VPU, get a video stream on the other end". It *clearly* doesn't have enough memory for that.
Very roughly, the procedure goes as is :
First, the user application must :
Get the first frame of the video stream Send it to the VPU driver Then VPU driver must :
Setup the VPU to decode the frame Launch the VPU decoding process Wait for the decoded result Send back the result to the user application. Then user application :
Retrieves and shows the result, Rinces and repeat for every frame of the video. So, yeah, VPU are not CODEC agnostics. They are CODEC specialized. So the driver is setup slowly, but surely, to decode each format correctly.

MPP/RKMPP is the RocKchip Media Process Platform.
A set of libraries, made by Rockchip, to communicate with their VPU driver. The thing is done in such a way that the "driver" basically only handle a few things like memory management.
The actual registers of the hardware are known by MPP and are setup by this library, then sent to the driver which almost blindly write the registers values into the hardware, or read them back and send them back to MPP.
Which mean that, even if you have the sources of the Rockchip VPU driver, you need the sources of MPP to understand how the hardware is actually programmed, based on the format you want to decode/encode.
This is the kind of setup which make you wonder, who's the real "driver" ?
http://opensource.rock-chips.com/wiki_Mpp
 
FFMPEG is one the most famous multimedia processing library and tool. This thing can combine audio/video from different sources and combine/convert them into a LOT of formats.
It comes as a library AND as a binary, which is one of the swiss-army knife for Audio-Video processing.
https://ffmpeg.org/
 
MPV is a Media Player, fork of Mplayer2, which use FFMPEG as a backend. It currently have a RKMPP backend to decode video frames using the RKMPP libraries.
https://mpv.io/
 
H264 is a video format.
https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC
 
The I-frames in H264 are reference (key) frames, from which other kind of frames (B/P frames) will be generated. The I-frame is basically the full frame, while the B/P frames are basically "patches" applied to I-frames to get the new picture.
The "patches" being generally smaller than the I frame, you get one way to "compress" the video (upon various others used simultaneously).
https://en.wikipedia.org/wiki/Inter_frame