drm/amd/display: check cursor scaling

Don't allow user-space to set different scaling parameters for the
cursor plane and for the primary plane. Because of DCE/DCN design,
it's not possible to have a mismatch.

The old check in dm_update_plane_state is superseded by this new
check.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
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>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -8975,13 +8975,6 @@ static int dm_update_plane_state(struct dc *dc,
 
 		new_acrtc = to_amdgpu_crtc(new_plane_crtc);
 
-		if ((new_plane_state->crtc_w > new_acrtc->max_cursor_width) ||
-			(new_plane_state->crtc_h > new_acrtc->max_cursor_height)) {
-			DRM_DEBUG_ATOMIC("Bad cursor size %d x %d\n",
-							 new_plane_state->crtc_w, new_plane_state->crtc_h);
-			return -EINVAL;
-		}
-
 		if (new_plane_state->src_x != 0 || new_plane_state->src_y != 0) {
 			DRM_DEBUG_ATOMIC("Cropping not supported for cursor plane\n");
 			return -EINVAL;
@@ -9135,6 +9128,43 @@ static int dm_update_plane_state(struct dc *dc,
 	return ret;
 }
 
+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;
+
+	/* 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. */
+
+	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) {
+		return 0;
+	}
+
+	cursor_scale_w = new_cursor_state->crtc_w * 1000 /
+			 (new_cursor_state->src_w >> 16);
+	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);
+
+	if (cursor_scale_w != primary_scale_w ||
+	    cursor_scale_h != primary_scale_h) {
+		DRM_DEBUG_ATOMIC("Cursor plane scaling doesn't match primary plane\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 static int add_affected_mst_dsc_crtcs(struct drm_atomic_state *state, struct drm_crtc *crtc)
 {
@@ -9347,6 +9377,13 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 	if (ret)
 		goto fail;
 
+	/* Check cursor planes scaling */
+	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
+		ret = dm_check_crtc_cursor(state, crtc, new_crtc_state);
+		if (ret)
+			goto fail;
+	}
+
 	if (state->legacy_cursor_update) {
 		/*
 		 * This is a fast cursor update coming from the plane update