[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>

1 files changed, 34 insertions, 7 deletions

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index 2c286c307145..37c334edc7e8 100644
--- 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);