Re: [PATCH v7 20/27] v4l: subdev: add V4L2_SUBDEV_ROUTE_FL_SOURCE

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

On Sun, Jun 06, 2021 at 01:44:54AM +0300, Laurent Pinchart wrote:
> On Mon, May 24, 2021 at 01:44:01PM +0300, Tomi Valkeinen wrote:
> > Add route flag to indicate that the route is a source route. This means
> > that the route does not lead anywhere, and the sink_pad and sink_stream
> > should not be used.
> 
> I don't like this much. It's not a route if it doesn't lead anywhere, so
> this flag seems like a hack. If we need a way to discover streams on a
> source, I'd rather have an explicit operation to do so. Can't the get
> frame descriptor operation be used for this ?
> 
> If the need is to find out that we're reaching the end of a pipeline
> while going through links and routes, I'd rather have a pad flag to
> indicate that the pad is an endpoint.

Also, I can't see where this is being used, so maybe we can just drop it
:-)

> > A sensor which provides multiple streams should implement get_routing
> > and use the flag to mark the routes as sources.
> > 
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> > ---
> >  include/uapi/linux/v4l2-subdev.h | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/include/uapi/linux/v4l2-subdev.h b/include/uapi/linux/v4l2-subdev.h
> > index 45c01799e2cd..f20491e1f53f 100644
> > --- a/include/uapi/linux/v4l2-subdev.h
> > +++ b/include/uapi/linux/v4l2-subdev.h
> > @@ -200,6 +200,13 @@ struct v4l2_subdev_capability {
> >   */
> >  #define V4L2_SUBDEV_ROUTE_FL_IMMUTABLE		BIT(1)
> >  
> > +/**
> > + * Is the route a source endpoint? A source endpoint route doesn't come
> > + * from "anywhere", and the sink_pad and sink_stream fields are unused.
> > + * Set by the driver.
> > + */
> > +#define V4L2_SUBDEV_ROUTE_FL_SOURCE		BIT(2)
> > +
> >  /**
> >   * struct v4l2_subdev_route - A route inside a subdev
> >   *

-- 
Regards,

Laurent Pinchart