RPI4B: what is needed for /dev/video10 to work ( v4l_m2m )

RPI4B: what is needed for /dev/video10 to work ( v4l_m2m )

[AL13N]

Hi,


I have a RPI4B with upstream kernel 6.1 64bit and there is no 
/dev/video10 present. I thought if I waited a bit more, it would appear 
in the kernel, but that was folly on my part.

Currently, watching a movie is painful since the software decoding is 
way too slow and it has very low fps on 1080p (or even 720p or even 
480p)

IIRC, someone told me something else has to be fixed before the codecs 
can be done, but I don't remember what it was, or i didn't find it in my 
email/the archives.

Can someone tell me what exactly needs to be done (in kernel) so that I 
can take a crack at it, (hopefully with some help)?

I don't remember if this was relevant, but there was some talk of 
needing to use opengl output with a specific texture format for it to 
work? or is that seperate?


Thanks in advance,

AL13N

Re: RPI4B: what is needed for /dev/video10 to work ( v4l_m2m )

[Maxime Ripard]

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Hi,

On Wed, Dec 27, 2023 at 04:19:19PM +0100, AL13N wrote:
> I have a RPI4B with upstream kernel 6.1 64bit and there is no /dev/video10
> present. I thought if I waited a bit more, it would appear in the kernel,
> but that was folly on my part.
> 
> Currently, watching a movie is painful since the software decoding is way
> too slow and it has very low fps on 1080p (or even 720p or even 480p)
> 
> IIRC, someone told me something else has to be fixed before the codecs can
> be done, but I don't remember what it was, or i didn't find it in my
> email/the archives.
> 
> Can someone tell me what exactly needs to be done (in kernel) so that I can
> take a crack at it, (hopefully with some help)?
> 
> I don't remember if this was relevant, but there was some talk of needing to
> use opengl output with a specific texture format for it to work? or is that
> seperate?

That's something for linux-media. The hardware codec isn't part of vc4
or v3d, it's a separate controller that requires a separate driver (in
v4l2).

That driver isn't upstream, and that would need the first thing to
tackle.

Maxime

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Re: RPI4B: what is needed for /dev/video10 to work ( v4l_m2m )

[Dave Stevenson]

On Tue, 2 Jan 2024 at 10:03, Maxime Ripard <mripard@kernel.org> wrote:
>
> Hi,
>
> On Wed, Dec 27, 2023 at 04:19:19PM +0100, AL13N wrote:
> > I have a RPI4B with upstream kernel 6.1 64bit and there is no /dev/video10
> > present. I thought if I waited a bit more, it would appear in the kernel,
> > but that was folly on my part.
> >
> > Currently, watching a movie is painful since the software decoding is way
> > too slow and it has very low fps on 1080p (or even 720p or even 480p)
> >
> > IIRC, someone told me something else has to be fixed before the codecs can
> > be done, but I don't remember what it was, or i didn't find it in my
> > email/the archives.
> >
> > Can someone tell me what exactly needs to be done (in kernel) so that I can
> > take a crack at it, (hopefully with some help)?
> >
> > I don't remember if this was relevant, but there was some talk of needing to
> > use opengl output with a specific texture format for it to work? or is that
> > seperate?
>
> That's something for linux-media. The hardware codec isn't part of vc4
> or v3d, it's a separate controller that requires a separate driver (in
> v4l2).
>
> That driver isn't upstream, and that would need the first thing to
> tackle.

IdeasOnBoard are working on our behalf to clean up the VCHIQ driver in
staging (hopefully unstaging it), and adding the mmal-vchiq, vcsm, and
ISP drivers. https://patchwork.linuxtv.org/project/linux-media/list/?series=11633
is probably the latest revision of the series, but there are a number
of supporting series around too.

The codec driver relies on the same mmal-vchiq and vcsm drivers as the
ISP, so adding that afterwards should be relatively simple.

Even though he's stepped back from being a maintainer, Stefan Wahren
is still keeping track of a number of the upstreaming tasks for the Pi
platform - see https://github.com/lategoodbye/rpi-zero/issues/43

  Dave

Re: RPI4B: what is needed for /dev/video10 to work ( v4l_m2m )

[AL13N]

Maxime Ripard schreef op 2024-01-02 11:03:
> Hi,
> 
> On Wed, Dec 27, 2023 at 04:19:19PM +0100, AL13N wrote:
>> I have a RPI4B with upstream kernel 6.1 64bit and there is no 
>> /dev/video10
>> present. I thought if I waited a bit more, it would appear in the 
>> kernel,
>> but that was folly on my part.
>> 
>> Currently, watching a movie is painful since the software decoding is 
>> way
>> too slow and it has very low fps on 1080p (or even 720p or even 480p)
>> 
>> IIRC, someone told me something else has to be fixed before the codecs 
>> can
>> be done, but I don't remember what it was, or i didn't find it in my
>> email/the archives.
>> 
>> Can someone tell me what exactly needs to be done (in kernel) so that 
>> I can
>> take a crack at it, (hopefully with some help)?
>> 
>> I don't remember if this was relevant, but there was some talk of 
>> needing to
>> use opengl output with a specific texture format for it to work? or is 
>> that
>> seperate?
> 
> That's something for linux-media. The hardware codec isn't part of vc4
> or v3d, it's a separate controller that requires a separate driver (in
> v4l2).
> 
> That driver isn't upstream, and that would need the first thing to
> tackle.
> 
> Maxime

Can I assume you're talking about the vchiq driver, which would have 
multiple things including codecs, or am I misunderstanding it?