[media] media: Check for active links on pads with MEDIA_PAD_FL_MUST_CONNECT flag

Do not allow streaming if a pad with MEDIA_PAD_FL_MUST_CONNECT flag is not
connected by an active link.
This patch makes it possible to avoid drivers having to check for the most
common case of link state validation: a sink pad that must be connected.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index 2c286c3..37c334e 100644 (file)
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -235,6 +235,8 @@ __must_check int media_entity_pipeline_start(struct media_entity *entity,
        media_entity_graph_walk_start(&graph, entity);
 
        while ((entity = media_entity_graph_walk_next(&graph))) {
+               DECLARE_BITMAP(active, entity->num_pads);
+               DECLARE_BITMAP(has_no_links, entity->num_pads);
                unsigned int i;
 
                entity->stream_count++;
@@ -248,21 +250,46 @@ __must_check int media_entity_pipeline_start(struct media_entity *entity,
                if (!entity->ops || !entity->ops->link_validate)
                        continue;
 
+               bitmap_zero(active, entity->num_pads);
+               bitmap_fill(has_no_links, entity->num_pads);
+
                for (i = 0; i < entity->num_links; i++) {
                        struct media_link *link = &entity->links[i];
-
-                       /* Is this pad part of an enabled link? */
-                       if (!(link->flags & MEDIA_LNK_FL_ENABLED))
-                               continue;
-
-                       /* Are we the sink or not? */
-                       if (link->sink->entity != entity)
+                       struct media_pad *pad = link->sink->entity == entity
+                                               ? link->sink : link->source;
+
+                       /* Mark that a pad is connected by a link. */
+                       bitmap_clear(has_no_links, pad->index, 1);
+
+                       /*
+                        * Pads that either do not need to connect or
+                        * are connected through an enabled link are
+                        * fine.
+                        */
+                       if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
+                           link->flags & MEDIA_LNK_FL_ENABLED)
+                               bitmap_set(active, pad->index, 1);
+
+                       /*
+                        * Link validation will only take place for
+                        * sink ends of the link that are enabled.
+                        */
+                       if (link->sink != pad ||
+                           !(link->flags & MEDIA_LNK_FL_ENABLED))
                                continue;
 
                        ret = entity->ops->link_validate(link);
                        if (ret < 0 && ret != -ENOIOCTLCMD)
                                goto error;
                }
+
+               /* Either no links or validated links are fine. */
+               bitmap_or(active, active, has_no_links, entity->num_pads);
+
+               if (!bitmap_full(active, entity->num_pads)) {
+                       ret = -EPIPE;
+                       goto error;
+               }
        }
 
        mutex_unlock(&mdev->graph_mutex);