Hi Hans, On Friday 21 June 2013 20:25:38 Hans Verkuil wrote: > Hi Guennadi, > > I had hoped to review this earlier this week, but I didn't get around it. > But better late than never... > > Comments below. > > On Mon June 17 2013 08:04:10 Guennadi Liakhovetski wrote: > > Add documentation for the V4L2 clock and V4L2 asynchronous probing APIs > > to v4l2-framework.txt. > > > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> > > --- > > > > Hopefully we can commit the actual patches now, while we refine the > > documentation. > > > > Documentation/video4linux/v4l2-framework.txt | 62 > > +++++++++++++++++++++++++- 1 files changed, 60 insertions(+), 2 > > deletions(-) > > > > diff --git a/Documentation/video4linux/v4l2-framework.txt > > b/Documentation/video4linux/v4l2-framework.txt index a300b28..159a83a > > 100644 > > --- a/Documentation/video4linux/v4l2-framework.txt > > +++ b/Documentation/video4linux/v4l2-framework.txt [snip] > > @@ -394,6 +413,25 @@ controlled through GPIO pins. This distinction is > > only relevant when setting up the device, but once the subdev is > > registered it is completely transparent. > > > > +In the asynchronous case subdevices register themselves using the > > +v4l2_async_register_subdev() function. Unregistration is performed, using > > +the v4l2_async_unregister_subdev() call. Subdevices registered this way > > +are stored on a global list of subdevices, ready to be picked up by > > +bridge drivers. > > + > > +Bridge drivers in turn have to register a notifier object with an array > > +of subdevice descriptors, that the bridge device needs for its operation. > > +This is performed using the v4l2_async_notifier_register() call. To > > +unregister the notifier the driver has to call > > +v4l2_async_notifier_unregister(). The former of the two functions takes > > +two arguments: a pointer to struct v4l2_device and a pointer to struct > > +v4l2_async_notifier. The latter contains a pointer to an array of > > +pointers to subdevice descriptors of type struct v4l2_async_subdev type. > > +The V4L2 core will then use these descriptors to match asynchronously > > +registered subdevices to them. If a match is detected the .bound() > > +notifier callback 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. > > Is that true? Don't you need at least a bound or a complete callback? A driver should implement at least either bound or complete, so in a sense all three callbacks are optional. This should probably be made a bit more explicit. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
