[PATCH v3 2/4] amd/display: add cursor alpha and blend mode checks

[Simon Ser]

We don't want a semi-transparent overlay to make the cursor plane
semi-transparent as well. Same for the pixel blend mode.

Signed-off-by: Simon Ser <cont...@emersion.fr>
Cc: Alex Deucher <alexander.deuc...@amd.com>
Cc: Harry Wentland <hwent...@amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlaus...@amd.com>
Cc: Michel Dänzer <mic...@daenzer.net>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index f60858112d3d..df40f74f5a15 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -9853,6 +9853,20 @@ static int dm_check_crtc_cursor(struct drm_atomic_state 
*state,
                        return -EINVAL;
                }
 
+               if (new_underlying_state->alpha != DRM_BLEND_ALPHA_OPAQUE) {
+                       drm_dbg_atomic(crtc->dev,
+                                      "Cursor [PLANE:%d:%s] can't be used with 
non-opaque underlying [PLANE:%d:%s]\n",
+                                      cursor->base.id, cursor->name, 
underlying->base.id, underlying->name);
+                       return -EINVAL;
+               }
+
+               if (new_underlying_state->pixel_blend_mode != 
DRM_MODE_BLEND_PREMULTI) {
+                       drm_dbg_atomic(crtc->dev,
+                                      "Cursor [PLANE:%d:%s] can't be used with 
non-premultiplied underlying [PLANE:%d:%s]\n",
+                                      cursor->base.id, cursor->name, 
underlying->base.id, underlying->name);
+                       return -EINVAL;
+               }
+
                /* If this plane covers the whole CRTC, no need to check planes 
underneath */
                if (new_underlying_state->crtc_x <= 0 &&
                    new_underlying_state->crtc_y <= 0 &&
-- 
2.41.0