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authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>2022-01-13 17:00:42 +0200
committerSakari Ailus <sakari.ailus@linux.intel.com>2022-03-04 00:27:06 +0200
commit3056a8e936bb090865402bfe6f3a730a28790033 (patch)
treedc9efe7ce7bb99f0264c24825220385ede80adf9 /drivers/media/mc
parentf17bc788f7b97c36b8f3fbef14555a2a16ee3f69 (diff)
media: media-entity: Simplify media_pipeline_start()
The media_pipeline_start() function has two purposes: it constructs a pipeline by recording the entities that are part of it, gathered from a graph walk, and validate the media links. The pipeline pointer is stored in the media_entity structure as part of this process, and the entity's stream count is increased, to record that the entity is streaming. When multiple video nodes are present in a pipeline, media_pipeline_start() is typically called on all of them, with the same pipeline pointer. This is taken into account in media_pipeline_start() by skipping validation for entities that are already part of the pipeline, while returning an error if an entity is part of a different pipeline. It turns out that this process is overly complicated. When media_pipeline_start() is called for the first time, it constructs the full pipeline, adding all entities and validating all the links. Subsequent calls to media_pipeline_start() are then nearly no-ops, they only increase the stream count on the pipeline and on all entities. The media_entity stream_count field is used for two purposes: checking if the entity is streaming, and detecting when a call to media_pipeline_stop() balances needs to reset the entity pipe pointer to NULL. The former can easily be replaced by a check of the pipe pointer. Simplify media_pipeline_start() by avoiding the pipeline walk on all calls but the first one, and drop the media_entity stream_count field. media_pipeline_stop() is updated accordingly. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> [Sakari Ailus: Drop redundant '!= NULL' as discussed] Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Diffstat (limited to 'drivers/media/mc')
-rw-r--r--drivers/media/mc/mc-entity.c52
1 files changed, 22 insertions, 30 deletions
diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index f83e043f0f3b..8ab0913d8d82 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -396,20 +396,21 @@ __must_check int __media_pipeline_start(struct media_entity *entity,
struct media_link *link;
int ret;
- if (!pipe->streaming_count++) {
- ret = media_graph_walk_init(&pipe->graph, mdev);
- if (ret)
- goto error_graph_walk_start;
+ if (pipe->streaming_count) {
+ pipe->streaming_count++;
+ return 0;
}
+ ret = media_graph_walk_init(&pipe->graph, mdev);
+ if (ret)
+ return ret;
+
media_graph_walk_start(&pipe->graph, entity);
while ((entity = media_graph_walk_next(graph))) {
DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
- entity->stream_count++;
-
if (entity->pipe && entity->pipe != pipe) {
pr_err("Pipe active for %s. Can't start for %s\n",
entity->name,
@@ -418,12 +419,12 @@ __must_check int __media_pipeline_start(struct media_entity *entity,
goto error;
}
- entity->pipe = pipe;
-
/* Already streaming --- no need to check. */
- if (entity->stream_count > 1)
+ if (entity->pipe)
continue;
+ entity->pipe = pipe;
+
if (!entity->ops || !entity->ops->link_validate)
continue;
@@ -479,6 +480,8 @@ __must_check int __media_pipeline_start(struct media_entity *entity,
}
}
+ pipe->streaming_count++;
+
return 0;
error:
@@ -489,24 +492,17 @@ error:
media_graph_walk_start(graph, entity_err);
while ((entity_err = media_graph_walk_next(graph))) {
- /* Sanity check for negative stream_count */
- if (!WARN_ON_ONCE(entity_err->stream_count <= 0)) {
- entity_err->stream_count--;
- if (entity_err->stream_count == 0)
- entity_err->pipe = NULL;
- }
+ entity_err->pipe = NULL;
/*
- * We haven't increased stream_count further than this
- * so we quit here.
+ * We haven't started entities further than this so we quit
+ * here.
*/
if (entity_err == entity)
break;
}
-error_graph_walk_start:
- if (!--pipe->streaming_count)
- media_graph_walk_cleanup(graph);
+ media_graph_walk_cleanup(graph);
return ret;
}
@@ -537,19 +533,15 @@ void __media_pipeline_stop(struct media_entity *entity)
if (WARN_ON(!pipe))
return;
+ if (--pipe->streaming_count)
+ return;
+
media_graph_walk_start(graph, entity);
- while ((entity = media_graph_walk_next(graph))) {
- /* Sanity check for negative stream_count */
- if (!WARN_ON_ONCE(entity->stream_count <= 0)) {
- entity->stream_count--;
- if (entity->stream_count == 0)
- entity->pipe = NULL;
- }
- }
+ while ((entity = media_graph_walk_next(graph)))
+ entity->pipe = NULL;
- if (!--pipe->streaming_count)
- media_graph_walk_cleanup(graph);
+ media_graph_walk_cleanup(graph);
}
EXPORT_SYMBOL_GPL(__media_pipeline_stop);