Re: [PATCH 2/4] media: dt-binding: media: Document rk3588’s vepu121

[Heiko Stübner]

Am Donnerstag, 21. März 2024, 10:19:54 CET schrieb Krzysztof Kozlowski:
> On 21/03/2024 09:47, Heiko Stübner wrote:
> >>>      enum:
> >>>        - rockchip,rk3568-vepu
> >>> +      - rockchip,rk3588-vepu121
> >>
> >> What is 121?
> > 
> > That is the strange naming of the ip block inside the soc.
> > 
> > I.e. the rk3588 TRM lists a number of different video encoders and decoders:
> > - VDPU121 is decoding h.263 and mpeg1,2,4
> > - VDPU381 is decoding h.265, h.264 and some more
> > - VDPU720 is decoding jpeg
> > - VDPU981 decodes AV1
> > - VEPU121 is the jpeg encoder above
> > - VEPU580 encodes h.264 and h.265
> > 
> > Each of those are separate IP blocks with their own io-memory, their own
> > interrupts and their own iommus, etc.
> 
> Thanks for explanation. Short introduction in commit msg would be nice
> (e.g. VEPU121, one of two VEPU encoders). OTOH, why not documenting all
> of them? Bindings are supposed to be as complete as possible.

We have a concurrent series for the vdpu121 running at
  https://lore.kernel.org/all/20240316071100.2419369-1-liujianfeng1994@xxxxxxxxx

I think not all of those encoders/decoders are based on the Hantro IP
or at least at the moment we don't know this yet.
Hence people adding compatibles for the blocks they have actually
managed to run on their hardware.

Bindings are supposed to be as complete as possible, but revising a wrong
binding later is very hard. And the whole media part is full of binary libraries
in the vendor kernel and has not the best documentation.

So I guess people are just cautious ;-)


Heiko