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

[Viktor Jägersküpper]

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.

Viktor