4 files changed, 32 insertions, 17 deletions

diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
index 88eedee018d3..f1dcad96f341 100644
--- a/drivers/gpu/drm/drm_blend.c
+++ b/drivers/gpu/drm/drm_blend.c
@@ -135,7 +135,9 @@
  *	are underneath planes with higher Z position values. Two planes with the
  *	same Z position value have undefined ordering. Note that the Z position
  *	value can also be immutable, to inform userspace about the hard-coded
- *	stacking of planes, see drm_plane_create_zpos_immutable_property().
+ *	stacking of planes, see drm_plane_create_zpos_immutable_property(). If
+ *	any plane has a zpos property (either mutable or immutable), then all
+ *	planes shall have a zpos property.
  *
  * pixel blend mode:
  *	Pixel blend mode is set up with drm_plane_create_blend_mode_property().
@@ -344,10 +346,10 @@ EXPORT_SYMBOL(drm_rotation_simplify);
  * should be set to 0 and max to maximal number of planes for given crtc - 1.
  *
  * If zpos of some planes cannot be changed (like fixed background or
- * cursor/topmost planes), driver should adjust min/max values and assign those
- * planes immutable zpos property with lower or higher values (for more
+ * cursor/topmost planes), drivers shall adjust the min/max values and assign
+ * those planes immutable zpos properties with lower or higher values (for more
  * information, see drm_plane_create_zpos_immutable_property() function). In such
- * case driver should also assign proper initial zpos values for all planes in
+ * case drivers shall also assign proper initial zpos values for all planes in
  * its plane_reset() callback, so the planes will be always sorted properly.
  *
  * See also drm_atomic_normalize_zpos().
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index d6ad60ab0d38..4af173ced327 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -289,6 +289,8 @@ EXPORT_SYMBOL(drm_universal_plane_init);
 
 int drm_plane_register_all(struct drm_device *dev)
 {
+	unsigned int num_planes = 0;
+	unsigned int num_zpos = 0;
 	struct drm_plane *plane;
 	int ret = 0;
 
@@ -297,8 +299,15 @@ int drm_plane_register_all(struct drm_device *dev)
 			ret = plane->funcs->late_register(plane);
 		if (ret)
 			return ret;
+
+		if (plane->zpos_property)
+			num_zpos++;
+		num_planes++;
 	}
 
+	drm_WARN(dev, num_zpos && num_planes != num_zpos,
+		 "Mixing planes with and without zpos property is invalid\n");
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_plane.c b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
index c6430027169f..a0021fc25b27 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_plane.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_plane.c
@@ -785,13 +785,15 @@ int rcar_du_planes_init(struct rcar_du_group *rgrp)
 
 		drm_plane_create_alpha_property(&plane->plane);
 
-		if (type == DRM_PLANE_TYPE_PRIMARY)
-			continue;
-
-		drm_object_attach_property(&plane->plane.base,
-					   rcdu->props.colorkey,
-					   RCAR_DU_COLORKEY_NONE);
-		drm_plane_create_zpos_property(&plane->plane, 1, 1, 7);
+		if (type == DRM_PLANE_TYPE_PRIMARY) {
+			drm_plane_create_zpos_immutable_property(&plane->plane,
+								 0);
+		} else {
+			drm_object_attach_property(&plane->plane.base,
+						   rcdu->props.colorkey,
+						   RCAR_DU_COLORKEY_NONE);
+			drm_plane_create_zpos_property(&plane->plane, 1, 1, 7);
+		}
 	}
 
 	return 0;
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
index 5e4faf258c31..f1a81c9b184d 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
@@ -392,12 +392,14 @@ int rcar_du_vsp_init(struct rcar_du_vsp *vsp, struct device_node *np,
 		drm_plane_helper_add(&plane->plane,
 				     &rcar_du_vsp_plane_helper_funcs);
 
-		if (type == DRM_PLANE_TYPE_PRIMARY)
-			continue;
-
-		drm_plane_create_alpha_property(&plane->plane);
-		drm_plane_create_zpos_property(&plane->plane, 1, 1,
-					       vsp->num_planes - 1);
+		if (type == DRM_PLANE_TYPE_PRIMARY) {
+			drm_plane_create_zpos_immutable_property(&plane->plane,
+								 0);
+		} else {
+			drm_plane_create_alpha_property(&plane->plane);
+			drm_plane_create_zpos_property(&plane->plane, 1, 1,
+						       vsp->num_planes - 1);
+		}
 	}
 
 	return 0;