+/*
+ * Propagate the alpha value through the pipeline.
+ *
+ * As the UDS has restricted scaling capabilities when the alpha component needs
+ * 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.
+ */
+void vsp1_pipeline_propagate_alpha(struct vsp1_pipeline *pipe,
+ struct vsp1_entity *input,
+ unsigned int alpha)
+{
+ struct vsp1_entity *entity;
+ struct media_pad *pad;
+
+ pad = media_entity_remote_pad(&input->pads[RWPF_PAD_SOURCE]);
+
+ while (pad) {
+ if (media_entity_type(pad->entity) != MEDIA_ENT_T_V4L2_SUBDEV)
+ break;
+
+ entity = to_vsp1_entity(media_entity_to_v4l2_subdev(pad->entity));
+
+ /* The BRU background color has a fixed alpha value set to 255,
+ * the output alpha value is thus always equal to 255.
+ */
+ if (entity->type == VSP1_ENTITY_BRU)
+ alpha = 255;
+
+ if (entity->type == VSP1_ENTITY_UDS) {
+ struct vsp1_uds *uds = to_uds(&entity->subdev);
+
+ vsp1_uds_set_alpha(uds, alpha);
+ break;
+ }
+
+ pad = &entity->pads[entity->source_pad];
+ pad = media_entity_remote_pad(pad);
+ }
+}
+