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

[Tetsuo Handa]

On 2026/07/30 6:45, Leandro Ribeiro 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.

Thank you. But could something like

  pr_warn("[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup. Please fix.", plane->base.id, plane->name);
  dump_stack();

be less prone to get oversighted (because of printing about 10+ lines)?