From 708f48e76d6de7a90e583e2b1e6b54be1a53cc1b Mon Sep 17 00:00:00 2001 From: Sakari Ailus Date: Tue, 18 Oct 2016 11:15:32 -0200 Subject: [PATCH] [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 Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/media/uapi/v4l/dev-codec.rst | 2 +- include/media/v4l2-mem2mem.h | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/Documentation/media/uapi/v4l/dev-codec.rst b/Documentation/media/uapi/v4l/dev-codec.rst index d9f218449ddd..c61e938bd8dc 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 1b355344c804..3ccd01bd245e 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 */ -- 2.20.1