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 <cont...@emersion.fr>
Cc: André Almeida <andrealm...@igalia.com>
Cc: Alex Deucher <alexander.deuc...@amd.com>
Cc: Christian König <christian.koe...@amd.com>
Cc: Michel Dänzer <michel.daen...@mailbox.org>
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/gpu/drm/drm_atomic_uapi.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c 
b/drivers/gpu/drm/drm_atomic_uapi.c
index 22bbb2d83e30..1764bb0dbbdf 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -1070,21 +1070,14 @@ int drm_atomic_set_property(struct drm_atomic_state 
*state,
                        break;
                }
 
-               if (async_flip && prop != config->prop_fb_id) {
+               if (async_flip && (prop != config->prop_fb_id ||
+                                  plane_state->plane->type != 
DRM_PLANE_TYPE_PRIMARY)) {
                        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);
-- 
2.45.2


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