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Qinyun Tan
313f798f52
Since commit860e748bdd("drm: ensure blend mode supported if pixel format with alpha exposed"), drm_mode_config_validate() warns when a plane exposes an alpha pixel format but not the "pixel blend mode" property. The ast cursor plane (ARGB4444, ARGB8888) trips this on driver load: [PLANE:37:plane-1] pixel format with alpha exposed but blend mode not setup WARNING: drivers/gpu/drm/drm_mode_config.c:872 at drm_mode_config_validate+0x48f/0x510 [drm] ... Call Trace: drm_dev_register+0x1ce/0x290 [drm] ast_pci_probe+0x19d/0x3f0 [ast] local_pci_probe+0x41/0x90 Per Thomas Zimmermann's review, the ASPEED documentation describes the hardware cursor as blending with straight (non-pre-multiplied) alpha, which corresponds to DRM_MODE_BLEND_COVERAGE. Expose a "pixel blend mode" property advertising only DRM_MODE_BLEND_COVERAGE to make the hardware semantics explicit and silence the warning. Fixes:860e748bdd("drm: ensure blend mode supported if pixel format with alpha exposed") Suggested-by: Thomas Zimmermann <[email protected]> Reviewed-by: Thomas Zimmermann <[email protected]> Tested-by: Thomas Zimmermann <[email protected]> Signed-off-by: Qinyun Tan <[email protected]> Signed-off-by: Thomas Zimmermann <[email protected]> Link: https://patch.msgid.link/[email protected]