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authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>2010-08-25 09:00:41 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-03-22 04:53:17 -0300
commite02188c90f6ef61f0844c42508fe603c5d4fa42b (patch)
tree7b0ff940b37ba6bf53c7cea7fadbb697ec2d156a /Documentation/DocBook
parent97548ed4c4661502cdfd1aabd5d3876fa4f5cc2e (diff)
[media] media: Pipelines and media streams
Drivers often need to associate pipeline objects to entities, and to take stream state into account when configuring entities and links. The pipeline API helps drivers manage that information. When starting streaming, drivers call media_entity_pipeline_start(). The function marks all entities connected to the given entity through enabled links, either directly or indirectly, as streaming. Similarly, when stopping the stream, drivers call media_entity_pipeline_stop(). The media_entity_pipeline_start() function takes a pointer to a media pipeline and stores it in every entity in the graph. Drivers should embed the media_pipeline structure in higher-level pipeline structures and can then access the pipeline through the media_entity structure. Link configuration will fail with -EBUSY by default if either end of the link is a streaming entity, unless the link is marked with the MEDIA_LNK_FL_DYNAMIC flag. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook')
-rw-r--r--Documentation/DocBook/v4l/media-ioc-enum-links.xml5
-rw-r--r--Documentation/DocBook/v4l/media-ioc-setup-link.xml3
2 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/media-ioc-enum-links.xml b/Documentation/DocBook/v4l/media-ioc-enum-links.xml
index 6da884159cab..d2fc73ef8d56 100644
--- a/Documentation/DocBook/v4l/media-ioc-enum-links.xml
+++ b/Documentation/DocBook/v4l/media-ioc-enum-links.xml
@@ -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>
diff --git a/Documentation/DocBook/v4l/media-ioc-setup-link.xml b/Documentation/DocBook/v4l/media-ioc-setup-link.xml
index 09ab3d2b3a52..2331e76ded17 100644
--- a/Documentation/DocBook/v4l/media-ioc-setup-link.xml
+++ b/Documentation/DocBook/v4l/media-ioc-setup-link.xml
@@ -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>