drm/amd/display: Check all enabled planes in dm_check_crtc_cursor

It was only checking planes which had any state changes in the same
commit. However, it also needs to check other enabled planes.

Not doing this meant that a commit might spuriously "succeed", resulting
in the cursor plane displaying with incorrect scaling. See
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3177#note_1824263
for an example.

Fixes: d1bfbe8a ("amd/display: check cursor plane matches underlying plane")
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Michel Dänzer <mdaenzer@redhat.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -10019,14 +10019,24 @@ static int dm_check_crtc_cursor(struct drm_atomic_state *state,
 	 * blending properties match the underlying planes'.
 	 */
 
-	new_cursor_state = drm_atomic_get_new_plane_state(state, cursor);
-	if (!new_cursor_state || !new_cursor_state->fb)
+	new_cursor_state = drm_atomic_get_plane_state(state, cursor);
+	if (IS_ERR(new_cursor_state))
+		return PTR_ERR(new_cursor_state);
+
+	if (!new_cursor_state->fb)
 		return 0;
 
 	dm_get_oriented_plane_size(new_cursor_state, &cursor_src_w, &cursor_src_h);
 	cursor_scale_w = new_cursor_state->crtc_w * 1000 / cursor_src_w;
 	cursor_scale_h = new_cursor_state->crtc_h * 1000 / cursor_src_h;
 
+	/* Need to check all enabled planes, even if this commit doesn't change
+	 * their state
+	 */
+	i = drm_atomic_add_affected_planes(state, crtc);
+	if (i)
+		return i;
+
 	for_each_new_plane_in_state_reverse(state, underlying, new_underlying_state, i) {
 		/* Narrow down to non-cursor planes on the same CRTC as the cursor */
 		if (new_underlying_state->crtc != crtc || underlying == crtc->cursor)