linux-kernel - Re: [PATCH v3] media: v4l2-ctrls: add full AV1 profile validation in validate_av1

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Message-ID: <CAKPKb8-s96v+Nh29Z5E0wgyXYgoFHJT2SHA_WpZshXspo0WY0w@mail.gmail.com>
Date: Thu, 23 Oct 2025 16:02:54 +0530
From: opensource india <opensource206@...il.com>
To: Hans Verkuil <hverkuil+cisco@...nel.org>
Cc: mchehab@...nel.org, hverkuil@...nel.org, ribalda@...omium.org, 
	laurent.pinchart@...asonboard.com, yunkec@...gle.com, 
	sakari.ailus@...ux.intel.com, james.cowgill@...ize.com, 
	Nicolas Dufresne <nicolas.dufresne@...labora.com>, linux-media@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] media: v4l2-ctrls: add full AV1 profile validation in validate_av1_sequence()

On Wed, Oct 22, 2025 at 12:44 PM Hans Verkuil <hverkuil+cisco@...nel.org> wrote:
>
> Hi Pavan,
>
> On 13/09/2025 12:52, Pavan Bobba wrote:
> > Complete the "TODO: PROFILES" by enforcing profile-specific and
> > monochrome constraints as defined by the AV1 specification
> > (Section 5.5.2, "Color config syntax").
> >
> > The validator now checks:
> >
> >  - Flags: reject any unknown bits set in sequence->flags
> >  - Profile range: only profiles 0..2 are valid
> >  - Profile 0: 8/10-bit only, subsampling must be 4:2:0 (sx=1, sy=1),
> >    monochrome allowed
> >  - Profile 1: 8/10-bit only, subsampling must be 4:4:4 (sx=0, sy=0),
> >    monochrome forbidden
> >  - Profile 2:
> >     * 8/10-bit: only 4:2:2 allowed (sx=1, sy=0)
> >     * 12-bit: 4:4:4 (sx=0, sy=0), 4:2:2 (sx=1, sy=0), or 4:2:0 (sx=1, sy=1)
> >       allowed
> >  - Monochrome path (all profiles except 1): forces subsampling_x=1,
> >    subsampling_y=1, separate_uv_delta_q=0
> >
> > These checks prevent userspace from providing invalid AV1 sequence
> > headers that would otherwise be accepted, leading to undefined driver
> > or hardware behavior.
>
> This patch was merged in our media-committers next branch, but I noticed that
> it now fails the v4l2-compliance test for the visl driver.
>
> The cause is that the new validation now fails with the default values for
> this control as set in std_init_compound().
>
> You can test this yourself by loading the visl driver and then running
> v4l2-compliance -d /dev/videoX -E --verbose
> (-E stops at the first error)
>
> Can you provide a patch to initialize this control with sane values?
>
> Apologies for not noticing this before: there are some issues with the automatic
> regression tests in our CI, so the tests weren't run.
>
> Regards,
>
>         Hans
>

Hi Hans Verkuil,

Thank you so much for the review.
yes, v4l2-compliance expected to fail indeed since it is sending
default values which, our newly added code rejects as per
specification

when you say patch, you mean patch for v4l2-compliance tool with
proper values so that v4l2 core driver can accept?