Re: [PATCH v2 1/1] drm: use drm_warn() in validate_blend_mode_for_alpha_formats()

[Maxime Ripard]

On Thu, Aug 27, 2026 at 01:25:18PM +0200, Viktor Jägersküpper wrote:
> On 8/14/26 15:42, Daniel Stone wrote:
> > Hi Leandro,
> > 
> > On Fri, 31 Jul 2026 at 16:43, Leandro Ribeiro
> > <leandro.ribeiro@xxxxxxxxxxxxx> wrote:
> >> Commit 860e748bddcc ("drm: ensure blend mode supported if pixel format
> >> with alpha exposed") introduced a WARN() to let driver developers know
> >> that a previously valid behavior should now be changed.
> >>
> >> But WARN() should not be used for that, as it's a kernel warning report
> >> mechanism for conditions that are not expected to happen. It also
> >> produces a stack trace. Instead, a simple warning-level log message
> >> should have been used, as drivers were expected to trigger the
> >> condition.
> >>
> >> This is causing problems for fuzzers, as they may stop when encountering
> >> a "BUG:" or "WARNING:" in the logs.
> >>
> >> Replace WARN() with drm_warn() in this function, avoiding these issues.
> >>
> >> Fixes: 860e748bddcc ("drm: ensure blend mode supported if pixel format with alpha exposed")
> >> Signed-off-by: Leandro Ribeiro <leandro.ribeiro@xxxxxxxxxxxxx>
> > 
> > Thanks, this is:
> > Reviewed-by: Daniel Stone <daniels@xxxxxxxxxxxxx>
> > 
> > I'll fix up the newline when applying.
> 
> Hi Maarten, Maxime and Thomas,
> 
> can you cherry-pick this fix for drm-misc-fixes and send a pull-request
> to Dave and Simona before the end of this week? I think this should land
> in rc1 because people are already complaining about the warnings and it
> will take some time to fix all affected drivers. I'm not even sure if
> those fixes can land in mainline after rc1.
> 
> If you don't have the time to do this or the other fixes in
> drm-misc-fixes are not yet ready for mainline, I will ask Linus to pick
> this fix directly.

This has been sent last week:
https://lore.kernel.org/dri-devel/20260820-fabulous-nimble-woodpecker-ffa695@houat/

Maxime

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