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Message-ID: <f490bd15fd8ee36cd3e759483bbcfb3288cace74.camel@ndufresne.ca>
Subject: Re: [PATCH 2/4] media: dt-binding: media: Document
 =?UTF-8?Q?rk3588=E2=80=99s?= vepu121
From: Nicolas Dufresne <nicolas@ndufresne.ca>
To: Heiko =?ISO-8859-1?Q?St=FCbner?= <heiko@sntech.de>, Emmanuel Gil Peyrot
 <linkmauve@linkmauve.fr>, linux-kernel@vger.kernel.org, Krzysztof Kozlowski
 <krzysztof.kozlowski@linaro.org>
Cc: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>, Philipp Zabel
 <p.zabel@pengutronix.de>, Mauro Carvalho Chehab <mchehab@kernel.org>, Rob
 Herring <robh@kernel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>,
 Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>, Robin Murphy
 <robin.murphy@arm.com>, Sebastian Reichel
 <sebastian.reichel@collabora.com>, Cristian Ciocaltea
 <cristian.ciocaltea@collabora.com>, Dragan Simic <dsimic@manjaro.org>, 
 Shreeya Patel <shreeya.patel@collabora.com>, Chris Morgan
 <macromorgan@hotmail.com>, Andy Yan <andy.yan@rock-chips.com>, Nicolas
 Frattaroli <frattaroli.nicolas@gmail.com>,  linux-media@vger.kernel.org,
 linux-rockchip@lists.infradead.org,  devicetree@vger.kernel.org,
 linux-arm-kernel@lists.infradead.org,  iommu@lists.linux.dev
Date: Fri, 22 Mar 2024 10:57:12 -0400
In-Reply-To: <2798331.BEx9A2HvPv@diego>
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Le jeudi 21 mars 2024 =C3=A0 10:32 +0100, Heiko St=C3=BCbner a =C3=A9crit=
=C2=A0:
> Am Donnerstag, 21. M=C3=A4rz 2024, 10:19:54 CET schrieb Krzysztof Kozlows=
ki:
> > On 21/03/2024 09:47, Heiko St=C3=BCbner wrote:
> > > > >      enum:
> > > > >        - rockchip,rk3568-vepu
> > > > > +      - rockchip,rk3588-vepu121
> > > >=20
> > > > What is 121?
> > >=20
> > > That is the strange naming of the ip block inside the soc.
> > >=20
> > > I.e. the rk3588 TRM lists a number of different video encoders and de=
coders:
> > > - 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
> > >=20
> > > Each of those are separate IP blocks with their own io-memory, their =
own
> > > interrupts and their own iommus, etc.
> >=20
> > 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.
>=20
> We have a concurrent series for the vdpu121 running at
>   https://lore.kernel.org/all/20240316071100.2419369-1-liujianfeng1994@gm=
ail.com
>=20
> 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.

Correct, on top of this legacy core, only VDPU981 (AV1 decode) is a chip fr=
om
Hantro / Verisilicon. Everything else looks like their own design and deriv=
ed
from their original rkvdec codec pack. We didn't name this AV1 decoder afte=
r VSI
brand as we didn't have the proper version information available, but we su=
spect
that is variant of their VSI9000D cores. In short, we tried to avoid docume=
nting
our speculation, even if we believe we are right.

>=20
> 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 li=
braries
> in the vendor kernel and has not the best documentation.

I agree with this, but I must give to RK that despite the lack of documenta=
tion,
their CODEC software is fully open-source and blob free on this platform.

>=20
> So I guess people are just cautious ;-)
>=20

exactly!

Nicolas