[PATCH v2] drm/atomic-helper: Make zpos property kerneldoc less misleading

[Thierry Reding]

From: Thierry Reding <treding at nvidia.com>

kerneldoc for drm_plane_create_zpos_property() says that the DRM core
will automatically calculate the normalized zpos values, but it doesn't
actually do that anymore since commit 38d868e41c4b ("drm: Don't force
all planes to be added to the state due to zpos"). Instead, drivers are
supposed to explicitly call the drm_atomic_normalize_zpos() function.
Change the kerneldoc comment to reflect that.

v2: reference the commit that introduced the kerneldoc unclarity

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Thierry Reding <treding at nvidia.com>
---
 drivers/gpu/drm/drm_blend.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
index 2e5e089dd912..4c62dff14893 100644
--- a/drivers/gpu/drm/drm_blend.c
+++ b/drivers/gpu/drm/drm_blend.c
@@ -214,9 +214,11 @@ EXPORT_SYMBOL(drm_rotation_simplify);
  * This function initializes generic mutable zpos property and enables support
  * for it in drm core. Drivers can then attach this property to planes to enable
  * support for configurable planes arrangement during blending operation.
- * Once mutable zpos property has been enabled, the DRM core will automatically
- * calculate &drm_plane_state.normalized_zpos values. Usually min should be set
- * to 0 and max to maximal number of planes for given crtc - 1.
+ * Drivers that attach a mutable zpos property to any plane should call the
+ * drm_atomic_normalize_zpos() helper during their implementation of
+ * &drm_mode_config_funcs.atomic_check(), which will update the normalized zpos
+ * values and store them in &drm_plane_state.normalized_zpos. Usually min
+ * 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
-- 
2.15.0