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-rw-r--r--drivers/gpu/drm/drm_blend.c10
-rw-r--r--drivers/gpu/drm/drm_plane.c9
2 files changed, 15 insertions, 4 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;
}