Re: [PATCH/RFC v2 14/15] adv748x: csi2: add get_routing support

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hi Kieran,

Thanks for your comments,

On 2017-12-14 23:27:57 +0000, Kieran Bingham wrote:
> Hi Niklas,
> 
> On 14/12/17 19:08, Niklas Söderlund wrote:
> > To support multiplexed streams the internal routing between the
> > adv748x sink pad and its source pad needs to be described.
> 
> The adv748x has quite a few sink and source pads... I presume here you mean the
> adv748x csi2 sink and source pad :D

Yes :-) Will fix for next version, thanks.

> 
> > 
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> > ---
> >  drivers/media/i2c/adv748x/adv748x-csi2.c | 22 ++++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> > 
> > diff --git a/drivers/media/i2c/adv748x/adv748x-csi2.c b/drivers/media/i2c/adv748x/adv748x-csi2.c
> > index 291b35bef49d41fb..dbefb53f5b8c414d 100644
> > --- a/drivers/media/i2c/adv748x/adv748x-csi2.c
> > +++ b/drivers/media/i2c/adv748x/adv748x-csi2.c
> > @@ -262,10 +262,32 @@ static int adv748x_csi2_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
> >  	return 0;
> >  }
> >  
> > +static int adv748x_csi2_get_routing(struct v4l2_subdev *subdev,
> > +				    struct v4l2_subdev_routing *routing)
> > +{
> > +	struct v4l2_subdev_route *r = routing->routes;
> > +
> > +	if (routing->num_routes < 1) {
> > +		routing->num_routes = 1;
> > +		return -ENOSPC;
> > +	}
> > +
> > +	routing->num_routes = 1;
> > +
> > +	r->sink_pad = ADV748X_CSI2_SINK;
> > +	r->sink_stream = 0;
> > +	r->source_pad = ADV748X_CSI2_SOURCE;
> > +	r->source_stream = 0;
> > +	r->flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE | V4L2_SUBDEV_ROUTE_FL_IMMUTABLE;
> > +
> > +	return 0;
> > +}
> > +
> 
> So - I think this is fine - but it seems a lot of code to define a static
> default route which describes a single link between it's sink pad - and its
> source pad ...
> 
> I suspect this should/could be wrapped by some helpers in core for cases like
> this, as it's the simple case - but as we don't currently have that I guess we
> have to put this in here for now ?

Yes for now we need to fill in the information here.

> 
> Maybe we should have a helper to make this

I'm sure there could be v4l2 helpers for such a case. I don't even think 
you wound need to prime it with any information. If there is only one 
source and one sink I'm sure a helper function can figure it out :-)

> 
> return v4l2_subdev_single_route(subdev, routing,
>                                 ADV748X_CS2_SINK, 0,
>                                 ADV748X_CSI2_SOURCE, 0,
>                   V4L2_SUBDEV_ROUTE_FL_ACTIVE | V4L2_SUBDEV_ROUTE_FL_IMMUTABLE);
> 
> Or maybe even define these static routes in a struct somehow?

For more complex setups a struct could be used together with a helper 
function to decode it. But then again maybe it's easier to just define a 
const v4l2_subdev_route array and 'routing->routes = my_const_routes' ?

> 
> >  static const struct v4l2_subdev_pad_ops adv748x_csi2_pad_ops = {
> >  	.get_fmt = adv748x_csi2_get_format,
> >  	.set_fmt = adv748x_csi2_set_format,
> >  	.get_frame_desc = adv748x_csi2_get_frame_desc,
> > +	.get_routing = adv748x_csi2_get_routing,
> >  	.s_stream = adv748x_csi2_s_stream,
> >  };
> >  
> > 

-- 
Regards,
Niklas Söderlund