Patch "drm/amd/display: Bail from dm_check_crtc_cursor if no relevant change" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/amd/display: Bail from dm_check_crtc_cursor if no relevant change

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amd-display-bail-from-dm_check_crtc_cursor-if-no.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 346daece5a34b54bd2b661886a3bad7d15bb46e9
Author: Michel Dänzer <mdaenzer@xxxxxxxxxx>
Date:   Mon Oct 2 16:16:49 2023 +0200

    drm/amd/display: Bail from dm_check_crtc_cursor if no relevant change
    
    [ Upstream commit bc0b79ce2050aa523c38c96b6d26340a96bfbdca ]
    
    If no plane was newly enabled or changed scaling, there can be no new
    scaling mismatch with the cursor plane.
    
    By not pulling non-cursor plane states into all atomic commits while
    the cursor plane is enabled, this avoids synchronizing all cursor plane
    changes to vertical blank, which caused the following IGT tests to fail:
    
    kms_cursor_legacy@cursor-vs-flip.*
    kms_cursor_legacy@flip-vs-cursor.*
    
    Fixes: 003048ddf44b ("drm/amd/display: Check all enabled planes in dm_check_crtc_cursor")
    Signed-off-by: Michel Dänzer <mdaenzer@xxxxxxxxxx>
    Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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 73db46b9e3e1a..42e266e074d1d 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -9641,10 +9641,12 @@ static int dm_check_crtc_cursor(struct drm_atomic_state *state,
 				struct drm_crtc *crtc,
 				struct drm_crtc_state *new_crtc_state)
 {
-	struct drm_plane *cursor = crtc->cursor, *underlying;
+	struct drm_plane *cursor = crtc->cursor, *plane, *underlying;
+	struct drm_plane_state *old_plane_state, *new_plane_state;
 	struct drm_plane_state *new_cursor_state, *new_underlying_state;
 	int i;
 	int cursor_scale_w, cursor_scale_h, underlying_scale_w, underlying_scale_h;
+	bool any_relevant_change = false;
 
 	/* On DCE and DCN there is no dedicated hardware cursor plane. We get a
 	 * cursor per pipe but it's going to inherit the scaling and
@@ -9652,6 +9654,35 @@ static int dm_check_crtc_cursor(struct drm_atomic_state *state,
 	 * blending properties match the underlying planes'.
 	 */
 
+	/* If no plane was enabled or changed scaling, no need to check again */
+	for_each_oldnew_plane_in_state(state, plane, old_plane_state, new_plane_state, i) {
+		int new_scale_w, new_scale_h, old_scale_w, old_scale_h;
+
+		if (!new_plane_state || !new_plane_state->fb || new_plane_state->crtc != crtc)
+			continue;
+
+		if (!old_plane_state || !old_plane_state->fb || old_plane_state->crtc != crtc) {
+			any_relevant_change = true;
+			break;
+		}
+
+		if (new_plane_state->fb == old_plane_state->fb &&
+		    new_plane_state->crtc_w == old_plane_state->crtc_w &&
+		    new_plane_state->crtc_h == old_plane_state->crtc_h)
+			continue;
+
+		dm_get_plane_scale(new_plane_state, &new_scale_w, &new_scale_h);
+		dm_get_plane_scale(old_plane_state, &old_scale_w, &old_scale_h);
+
+		if (new_scale_w != old_scale_w || new_scale_h != old_scale_h) {
+			any_relevant_change = true;
+			break;
+		}
+	}
+
+	if (!any_relevant_change)
+		return 0;
+
 	new_cursor_state = drm_atomic_get_plane_state(state, cursor);
 	if (IS_ERR(new_cursor_state))
 		return PTR_ERR(new_cursor_state);