On Thu, Sep 10, 2026 at 9:25 PM Roshan Kumar <[email protected]> wrote:
> The PL110/PL111 controller scans out a single framebuffer and never
> blends its alpha channel with anything. In every pixel-format table
> each alpha-carrying entry (ARGB/ABGR in 8888, 1555 and 4444) maps to
> exactly the same register configuration as its XRGB/XBGR counterpart,
> so the alpha byte was never used by the hardware.
>
> Commit 860e748bddcc ("drm: ensure blend mode supported if pixel format
> with alpha exposed") added validation that warns when a plane exposes
> alpha formats without a pixel blend mode property, and PL111 does exactly
> that. With panic_on_warn enabled the warning prevents the syzkaller
> vexpress-a15 manager from booting.
>
> Drivers should not report formats they do not support, so remove the
> alpha formats from all variant tables: the generic PL110, PL111 and
> Nomadik tables in pl111_drv.c and the board-specific Integrator, IM-PD1,
> Versatile and RealView/Versatile-Express tables in pl111_versatile.c,
> plus the now dead case labels in the display setup and the Versatile
> syscon connector switch, instead of advertising a blend mode property.
> Behavior is unchanged for userspace that picks an XRGB/XBGR/RGB format;
> alpha-picking clients fall back to the identical X variant.
>
> Link: https://github.com/google/syzkaller/issues/7805
> Fixes: 860e748bddcc ("drm: ensure blend mode supported if pixel format with
> alpha exposed")
> Signed-off-by: Roshan Kumar <[email protected]>
Patch applied to drm-misc-next with Thomas' review tag.
Yours,
Linus Walleij
