[PATCH v2.2 2/4] media: Check for active links on pads with MEDIA_PAD_FL_MUST_CONNECT flag

Sakari Ailus
2013-10-15T21:48:50Z

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>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
drivers/media/media-entity.c | 41 ++++++++++++++++++++++++++++++++++-------
1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index 2c286c3..37c334e 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);
--
1.7.10.4