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authorSakari Ailus <sakari.ailus@linux.intel.com>2016-10-18 11:15:32 -0200
committerMauro Carvalho Chehab <mchehab@s-opensource.com>2016-11-16 13:29:44 -0200
commit708f48e76d6de7a90e583e2b1e6b54be1a53cc1b (patch)
treee2cdd148abcfac520c4cea30343997c3e63cadf1
parent20d93338bf250f3f6adeb71cc234fca966ef51d7 (diff)
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[media] v4l: Document that m2m devices have a file handle specific context
Memory-to-memory V4L2 devices all have file handle specific context. Say this in the API documentation so that the user space may rely on it being the case. Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
-rw-r--r--Documentation/media/uapi/v4l/dev-codec.rst2
-rw-r--r--include/media/v4l2-mem2mem.h3
2 files changed, 4 insertions, 1 deletions
diff --git a/Documentation/media/uapi/v4l/dev-codec.rst b/Documentation/media/uapi/v4l/dev-codec.rst
index d9f2184..c61e938 100644
--- a/Documentation/media/uapi/v4l/dev-codec.rst
+++ b/Documentation/media/uapi/v4l/dev-codec.rst
@@ -26,7 +26,7 @@ parameters
The MPEG controls actually support many more codecs than
just MPEG. See :ref:`mpeg-controls`.
-Memory-to-memory devices can often be used as a shared resource: you can
+Memory-to-memory devices function as a shared resource: you can
open the video node multiple times, each application setting up their
own codec properties that are local to the file handle, and each can use
it independently from the others. The driver will arbitrate access to
diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index 1b35534..3ccd01b 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -90,6 +90,9 @@ struct v4l2_m2m_queue_ctx {
* %TRANS_QUEUED, %TRANS_RUNNING and %TRANS_ABORT.
* @finished: Wait queue used to signalize when a job queue finished.
* @priv: Instance private data
+ *
+ * The memory to memory context is specific to a file handle, NOT to e.g.
+ * a device.
*/
struct v4l2_m2m_ctx {
/* optional cap/out vb2 queues lock */
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