@@ -179,6 +179,11 @@
<entry>The link enabled state can't be modified at runtime. An
immutable link is always enabled.</entry>
</row>
+ <row>
+ <entry><constant>MEDIA_LNK_FL_DYNAMIC</constant></entry>
+ <entry>The link enabled state can be modified during streaming. This
+ flag is set by drivers and is read-only for applications.</entry>
+ </row>
</tbody>
</tgroup>
</table>
@@ -60,6 +60,9 @@
<para>Link configuration has no side effect on other links. If an enabled
link at the sink pad prevents the link from being enabled, the driver
returns with an &EBUSY;.</para>
+ <para>Only links marked with the <constant>DYNAMIC</constant> link flag can
+ be enabled/disabled while streaming media data. Attempting to enable or
+ disable a streaming non-dynamic link will return an &EBUSY;.</para>
<para>If the specified link can't be found the driver returns with an
&EINVAL;.</para>
</refsect1>
@@ -313,3 +313,41 @@ Link configuration must not have any side effect on other links. If an enabled
link at a sink pad prevents another link at the same pad from being disabled,
the link_setup operation must return -EBUSY and can't implicitly disable the
first enabled link.
+
+
+Pipelines and media streams
+---------------------------
+
+When starting streaming, drivers must notify all entities in the pipeline to
+prevent link states from being modified during streaming by calling
+
+ media_entity_pipeline_start(struct media_entity *entity,
+ struct media_pipeline *pipe);
+
+The function will mark all entities connected to the given entity through
+enabled links, either directly or indirectly, as streaming.
+
+The media_pipeline instance pointed to by the pipe argument will be stored in
+every entity in the pipeline. Drivers should embed the media_pipeline structure
+in higher-level pipeline structures and can then access the pipeline through
+the media_entity pipe field.
+
+Calls to media_entity_pipeline_start() can be nested. The pipeline pointer must
+be identical for all nested calls to the function.
+
+When stopping the stream, drivers must notify the entities with
+
+ media_entity_pipeline_stop(struct media_entity *entity);
+
+If multiple calls to media_entity_pipeline_start() have been made the same
+number of media_entity_pipeline_stop() calls are required to stop streaming. The
+media_entity pipe field is reset to NULL on the last nested stop call.
+
+Link configuration will fail with -EBUSY by default if either end of the link is
+a streaming entity. Links that can be modified while streaming must be marked
+with the MEDIA_LNK_FL_DYNAMIC flag.
+
+If other operations need to be disallowed on streaming entities (such as
+changing entities configuration parameters) drivers can explictly check the
+media_entity stream_count field to find out if an entity is streaming. This
+operation must be done with the media_device graph_mutex held.
@@ -197,6 +197,75 @@ media_entity_graph_walk_next(struct media_entity_graph *graph)
EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
/* -----------------------------------------------------------------------------
+ * Pipeline management
+ */
+
+/**
+ * media_entity_pipeline_start - Mark a pipeline as streaming
+ * @entity: Starting entity
+ * @pipe: Media pipeline to be assigned to all entities in the pipeline.
+ *
+ * Mark all entities connected to a given entity through enabled links, either
+ * directly or indirectly, as streaming. The given pipeline object is assigned to
+ * every entity in the pipeline and stored in the media_entity pipe field.
+ *
+ * Calls to this function can be nested, in which case the same number of
+ * media_entity_pipeline_stop() calls will be required to stop streaming. The
+ * pipeline pointer must be identical for all nested calls to
+ * media_entity_pipeline_start().
+ */
+void media_entity_pipeline_start(struct media_entity *entity,
+ struct media_pipeline *pipe)
+{
+ struct media_device *mdev = entity->parent;
+ struct media_entity_graph graph;
+
+ mutex_lock(&mdev->graph_mutex);
+
+ media_entity_graph_walk_start(&graph, entity);
+
+ while ((entity = media_entity_graph_walk_next(&graph))) {
+ entity->stream_count++;
+ WARN_ON(entity->pipe && entity->pipe != pipe);
+ entity->pipe = pipe;
+ }
+
+ mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
+
+/**
+ * media_entity_pipeline_stop - Mark a pipeline as not streaming
+ * @entity: Starting entity
+ *
+ * Mark all entities connected to a given entity through enabled links, either
+ * directly or indirectly, as not streaming. The media_entity pipe field is
+ * reset to NULL.
+ *
+ * If multiple calls to media_entity_pipeline_start() have been made, the same
+ * number of calls to this function are required to mark the pipeline as not
+ * streaming.
+ */
+void media_entity_pipeline_stop(struct media_entity *entity)
+{
+ struct media_device *mdev = entity->parent;
+ struct media_entity_graph graph;
+
+ mutex_lock(&mdev->graph_mutex);
+
+ media_entity_graph_walk_start(&graph, entity);
+
+ while ((entity = media_entity_graph_walk_next(&graph))) {
+ entity->stream_count--;
+ if (entity->stream_count == 0)
+ entity->pipe = NULL;
+ }
+
+ mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
+
+/* -----------------------------------------------------------------------------
* Module use count
*/
@@ -364,6 +433,10 @@ int __media_entity_setup_link(struct media_link *link, u32 flags)
source = link->source->entity;
sink = link->sink->entity;
+ if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
+ (source->stream_count || sink->stream_count))
+ return -EBUSY;
+
mdev = source->parent;
if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify) {
@@ -106,6 +106,7 @@ struct media_pad_desc {
#define MEDIA_LNK_FL_ENABLED (1 << 0)
#define MEDIA_LNK_FL_IMMUTABLE (1 << 1)
+#define MEDIA_LNK_FL_DYNAMIC (1 << 2)
struct media_link_desc {
struct media_pad_desc source;
@@ -26,6 +26,9 @@
#include <linux/list.h>
#include <linux/media.h>
+struct media_pipeline {
+};
+
struct media_link {
struct media_pad *source; /* Source pad */
struct media_pad *sink; /* Sink pad */
@@ -67,8 +70,11 @@ struct media_entity {
const struct media_entity_operations *ops; /* Entity operations */
+ int stream_count; /* Stream count for the entity. */
int use_count; /* Use count for the entity. */
+ struct media_pipeline *pipe; /* Pipeline this entity belongs to. */
+
union {
/* Node specifications */
struct {
@@ -114,6 +120,7 @@ struct media_entity_graph {
int media_entity_init(struct media_entity *entity, u16 num_pads,
struct media_pad *pads, u16 extra_links);
void media_entity_cleanup(struct media_entity *entity);
+
int media_entity_create_link(struct media_entity *source, u16 source_pad,
struct media_entity *sink, u16 sink_pad, u32 flags);
int __media_entity_setup_link(struct media_link *link, u32 flags);
@@ -129,6 +136,9 @@ void media_entity_graph_walk_start(struct media_entity_graph *graph,
struct media_entity *entity);
struct media_entity *
media_entity_graph_walk_next(struct media_entity_graph *graph);
+void media_entity_pipeline_start(struct media_entity *entity,
+ struct media_pipeline *pipe);
+void media_entity_pipeline_stop(struct media_entity *entity);
#define media_entity_call(entity, operation, args...) \
(((entity)->ops && (entity)->ops->operation) ? \