Hejssan! On Thu, Jun 29, 2017 at 09:21:53AM +0200, Niklas Söderlund wrote: > Hi Sakari, > > Thanks for your patch. > > On 2017-06-29 09:38:53 +0300, Sakari Ailus wrote: > > As we begin to add support for systems with media pipelines controlled by > > more than one device driver, it is essential that we precisely define the > > responsibilities of each component in the stream control and common > > practices. > > > > Specifically, this patch documents two things: > > > > 1) streaming control is done per sub-device and sub-device drivers > > themselves are responsible for streaming setup in upstream sub-devices and > > > > 2) broken frames should be tolerated at streaming stop. It is the > > responsibility of the sub-device driver to stop the transmitter after > > itself if it cannot handle broken frames (and it should be probably be > > done anyway). > > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > --- > > Documentation/media/kapi/v4l2-subdev.rst | 36 ++++++++++++++++++++++++++++++++ > > 1 file changed, 36 insertions(+) > > > > diff --git a/Documentation/media/kapi/v4l2-subdev.rst b/Documentation/media/kapi/v4l2-subdev.rst > > index e1f0b72..27e371e 100644 > > --- a/Documentation/media/kapi/v4l2-subdev.rst > > +++ b/Documentation/media/kapi/v4l2-subdev.rst > > @@ -262,6 +262,42 @@ is called. After all subdevices have been located the .complete() callback is > > called. When a subdevice is removed from the system the .unbind() method is > > called. All three callbacks are optional. > > > > +Streaming control > > +^^^^^^^^^^^^^^^^^ > > + > > +Starting and stopping the stream are somewhat complex operations that > > +often require walking the media graph to enable streaming on > > +sub-devices which the pipeline consists of. This involves interaction > > +between multiple drivers, sometimes more than two. > > + > > +The ``.s_stream()`` core op is responsible for starting and stopping > > .s_stream() is a video or audio op not a core op right? But at the same > time it's all part of the v4l2 core :-) Apart from this nit-pick which > I'm fine to leave as is at your leisure. > > Acked-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx> Good point. The audio s_stream() op appears to be much less used and not by MC enabled drivers. I'll fix that, as well as add a proper reference to struct v4l2_subdev_video_ops. -- Hälsningar, Sakari Ailus e-mail: sakari.ailus@xxxxxx XMPP: sailus@xxxxxxxxxxxxxx
