Re: [PATCH] drm/amd/display: Fix direct scanout alpha on some DRM_FORMATs

[Harry Wentland]

On 2026-09-30 12:25, sunpeng...@amd.com wrote:

From: Leo Li <sunpeng...@amd.com>

[Why]

DM was declaring it's own list of has_alpha DRM formats to check against
for enabling alpha blending, when the format->has_alpha already does
that for us.

The self-declared list missed some has_alpha formats, causing
direct-scanout planes with such formats to appear opaque.

[How]

Drop the self-declared list, instead use the format->has_alpha field
directly.

Cc: sta...@vger.kernel.org
Signed-off-by: Leo Li <sunpeng...@amd.com>

Reviewed-by: Harry Wentland <harry.wentl...@amd.com>

Harry

---
  .../amd/display/amdgpu_dm/amdgpu_dm_plane.c   | 20 +------------------
  1 file changed, 1 insertion(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
index 0b5c4be1b3ec1..df6784d58c382 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
@@ -113,25 +113,7 @@ void amdgpu_dm_plane_fill_blending_from_plane_state(const 
struct drm_plane_state

if (plane_state->pixel_blend_mode == DRM_MODE_BLEND_PREMULTI ||

                plane_state->pixel_blend_mode == DRM_MODE_BLEND_COVERAGE) {
-               static const uint32_t alpha_formats[] = {
-                       DRM_FORMAT_ARGB8888,
-                       DRM_FORMAT_RGBA8888,
-                       DRM_FORMAT_ABGR8888,
-                       DRM_FORMAT_ARGB2101010,
-                       DRM_FORMAT_ABGR2101010,
-                       DRM_FORMAT_ARGB16161616,
-                       DRM_FORMAT_ABGR16161616,
-                       DRM_FORMAT_ARGB16161616F,
-               };
-               uint32_t format = plane_state->fb->format->format;
-               unsigned int i;
-
-               for (i = 0; i < ARRAY_SIZE(alpha_formats); ++i) {
-                       if (format == alpha_formats[i]) {
-                               *per_pixel_alpha = true;
-                               break;
-                       }
-               }
+               *per_pixel_alpha = plane_state->fb->format->has_alpha;

if (*per_pixel_alpha && plane_state->pixel_blend_mode == DRM_MODE_BLEND_COVERAGE)

                        *pre_multiplied_alpha = false;