[media] v4l: vsp1: Document calling context of vsp1_pipeline_propagate_alpha()

The function can only be called from a s_stream handler as it requires a
valid display list context (due to calling vsp1_uds_set_alpha() which
writes to module registers). Document the requirement.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/platform/vsp1/vsp1_pipe.c b/drivers/media/platform/vsp1/vsp1_pipe.c
index cb67b8f806358765887a1b1d3bb0765d361f5e5b..a9a754e17e8d37bb0eeb018db4f3d2c84c0e20f4 100644 (file)
--- a/drivers/media/platform/vsp1/vsp1_pipe.c
+++ b/drivers/media/platform/vsp1/vsp1_pipe.c
@@ -318,6 +318,9 @@ done:
  * to be scaled, we disable alpha scaling when the UDS input has a fixed alpha
  * value. The UDS then outputs a fixed alpha value which needs to be programmed
  * from the input RPF alpha.
+ *
+ * This function can only be called from a subdev s_stream handler as it
+ * requires a valid display list context.
  */
 void vsp1_pipeline_propagate_alpha(struct vsp1_pipeline *pipe,
                                   struct vsp1_entity *input,