[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>

diff --git a/Documentation/media/uapi/v4l/dev-codec.rst b/Documentation/media/uapi/v4l/dev-codec.rst
index d9f218449ddd3bf9f46530bf0e8e15e442681b55..c61e938bd8dcc36e964c9737c3d405132ec5b35c 100644 (file)
--- 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 1b355344c804070a93ab788697306f3a1d869c49..3ccd01bd245e8926bc2012eb5ea9360242a75020 100644 (file)
--- 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 */