amd/display: check cursor plane matches underlying plane

The current logic checks whether the cursor plane blending
properties match the primary plane's. However that's wrong,
because the cursor is painted on all planes underneath. If
the cursor is over the primary plane and the overlay plane,
it's painted on both pipes.

Iterate over the CRTC planes and check their scaling match
the cursor's.

v4: fix typo in commit message (Harry)
Signed-off-by: Simon Ser <contact@emersion.fr>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -10535,18 +10535,18 @@ 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_state *new_cursor_state, *new_primary_state;
-	int cursor_scale_w, cursor_scale_h, primary_scale_w, primary_scale_h;
+	struct drm_plane *cursor = crtc->cursor, *underlying;
+	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;
 
 	/* 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
 	 * positioning from the underlying pipe. Check the cursor plane's
-	 * blending properties match the primary plane's. */
+	 * blending properties match the underlying planes'. */
 
-	new_cursor_state = drm_atomic_get_new_plane_state(state, crtc->cursor);
-	new_primary_state = drm_atomic_get_new_plane_state(state, crtc->primary);
-	if (!new_cursor_state || !new_primary_state ||
-	    !new_cursor_state->fb || !new_primary_state->fb) {
+	new_cursor_state = drm_atomic_get_new_plane_state(state, cursor);
+	if (!new_cursor_state || !new_cursor_state->fb) {
 		return 0;
 	}
 
@@ -10555,15 +10555,34 @@ static int dm_check_crtc_cursor(struct drm_atomic_state *state,
 	cursor_scale_h = new_cursor_state->crtc_h * 1000 /
 			 (new_cursor_state->src_h >> 16);
 
-	primary_scale_w = new_primary_state->crtc_w * 1000 /
-			 (new_primary_state->src_w >> 16);
-	primary_scale_h = new_primary_state->crtc_h * 1000 /
-			 (new_primary_state->src_h >> 16);
+	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)
+			continue;
 
-	if (cursor_scale_w != primary_scale_w ||
-	    cursor_scale_h != primary_scale_h) {
-		drm_dbg_atomic(crtc->dev, "Cursor plane scaling doesn't match primary plane\n");
-		return -EINVAL;
+		/* Ignore disabled planes */
+		if (!new_underlying_state->fb)
+			continue;
+
+		underlying_scale_w = new_underlying_state->crtc_w * 1000 /
+				     (new_underlying_state->src_w >> 16);
+		underlying_scale_h = new_underlying_state->crtc_h * 1000 /
+				     (new_underlying_state->src_h >> 16);
+
+		if (cursor_scale_w != underlying_scale_w ||
+		    cursor_scale_h != underlying_scale_h) {
+			drm_dbg_atomic(crtc->dev,
+				       "Cursor [PLANE:%d:%s] scaling doesn't match 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 &&
+		    new_underlying_state->crtc_x + new_underlying_state->crtc_w >= new_crtc_state->mode.hdisplay &&
+		    new_underlying_state->crtc_y + new_underlying_state->crtc_h >= new_crtc_state->mode.vdisplay)
+			break;
 	}
 
 	return 0;