drm/atomic: allow no-op FB_ID updates for async flips

User-space is allowed to submit any property in an async flip as
long as the value doesn't change. However we missed one case:
as things stand, the kernel rejects no-op FB_ID changes on
non-primary planes. Fix this by changing the conditional and
skipping drm_atomic_check_prop_changes() only for FB_ID on the
primary plane (instead of skipping for FB_ID on any plane).

Fixes: 0e26cc72c71c ("drm: Refuse to async flip with atomic prop changes")
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Tested-by: Xaver Hugl <xaver.hugl@kde.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Michel Dänzer <michel.daenzer@mailbox.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240731191014.878320-1-contact@emersion.fr

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 7609c798d73dfba57497c36295cbc8b4f0819982..7936c20239551817bc8236ef6c1f65606084a39d 100644 (file)
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -1071,23 +1071,16 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
                }
 
                if (async_flip &&
-                   prop != config->prop_fb_id &&
-                   prop != config->prop_in_fence_fd &&
-                   prop != config->prop_fb_damage_clips) {
+                   (plane_state->plane->type != DRM_PLANE_TYPE_PRIMARY ||
+                    (prop != config->prop_fb_id &&
+                     prop != config->prop_in_fence_fd &&
+                     prop != config->prop_fb_damage_clips))) {
                        ret = drm_atomic_plane_get_property(plane, plane_state,
                                                            prop, &old_val);
                        ret = drm_atomic_check_prop_changes(ret, old_val, prop_value, prop);
                        break;
                }
 
-               if (async_flip && plane_state->plane->type != DRM_PLANE_TYPE_PRIMARY) {
-                       drm_dbg_atomic(prop->dev,
-                                      "[OBJECT:%d] Only primary planes can be changed during async flip\n",
-                                      obj->id);
-                       ret = -EINVAL;
-                       break;
-               }
-
                ret = drm_atomic_plane_set_property(plane,
                                plane_state, file_priv,
                                prop, prop_value);