[PATCH] drm: rcar-du: Create immutable zpos property for primary planes

[Laurent Pinchart]

The R-Car DU driver creates a zpos property, ranging from 1 to 7, for
all the overlay planes, but leaves the primary plane without a zpos
property. The DRM/KMS API doesn't clearly specify if this is acceptable,
of it the property is mandatory for all planes when exposed for some of
the planes. Nonetheless, weston v8.0 has been reported to have trouble
handling this situation.

The DRM core offers support for immutable zpos properties. Creating an
immutable zpos property set to 0 for the primary planes seems to be a
good way forward, as it shouldn't introduce any regression, and can fix
the issue. Do so.

Reported-by: Kuninori Morimoto <kuninori.morimoto.gx at renesas.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
---
 drivers/gpu/drm/rcar-du/rcar_du_plane.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

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;
-- 
Regards,

Laurent Pinchart