Re: [PATCH v9 07/28] rcar-vin: change name of video device

Niklas Söderlund
2018-01-08T16:42:08Z

Hi Laurent,

On 2018-01-08 18:35:23 +0200, Laurent Pinchart wrote:
> Hi Niklas,
>
> On Wednesday, 20 December 2017 17:20:55 EET Niklas Söderlund wrote:
> > On 2017-12-14 17:50:24 +0200, Laurent Pinchart wrote:
> > > On Thursday, 14 December 2017 16:25:00 EET Sakari Ailus wrote:
> > >> On Fri, Dec 08, 2017 at 10:17:36AM +0200, Laurent Pinchart wrote:
> > >>> On Friday, 8 December 2017 03:08:21 EET Niklas Söderlund wrote:
> > >>>> The rcar-vin driver needs to be part of a media controller to
> > >>>> support Gen3. Give each VIN instance a unique name so it can be
> > >>>> referenced from userspace.
> > >>>>
> > >>>> Signed-off-by: Niklas Söderlund
> > >>>> <niklas.soderlund+renesas@ragnatech.se>
> > >>>> Reviewed-by: Kieran Bingham
> > >>>> <kieran.bingham+renesas@ideasonboard.com>
> > >>>> Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
> > >>>> ---
> > >>>>
> > >>>> drivers/media/platform/rcar-vin/rcar-v4l2.c | 3 ++-
> > >>>> 1 file changed, 2 insertions(+), 1 deletion(-)
> > >>>>
> > >>>> diff --git a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > >>>> b/drivers/media/platform/rcar-vin/rcar-v4l2.c index
> > >>>> 59ec6d3d119590aa..19de99133f048960 100644
> > >>>> --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > >>>> +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> > >>>> @@ -876,7 +876,8 @@ int rvin_v4l2_register(struct rvin_dev *vin)
> > >>>> vdev->fops = &rvin_fops;
> > >>>> vdev->v4l2_dev = &vin->v4l2_dev;
> > >>>> vdev->queue = &vin->queue;
> > >>>> - strlcpy(vdev->name, KBUILD_MODNAME, sizeof(vdev->name));
> > >>>> + snprintf(vdev->name, sizeof(vdev->name), "%s %s", KBUILD_MODNAME,
> > >>>> + dev_name(vin->dev));
> > >>>
> > >>> Do we need the module name here ? How about calling them "%s output",
> > >>> dev_name(vin->dev) to emphasize the fact that this is a video node and
> > >>> not a VIN subdev ? This is what the omap3isp and vsp1 drivers do.
> > >>>
> > >>> We're suffering a bit from the fact that V4L2 has never standardized a
> > >>> naming scheme for the devices. It wouldn't be fair to ask you to fix
> > >>> that as a prerequisite to get the VIN driver merged, but we clearly have
> > >>> to work on that at some point.
> > >>
> > >> Agreed, this needs to be stable and I think aligning to what omap3isp or
> > >> vsp1 do would be a good fix here.
> > >
> > > Even omap3isp and vsp1 are not fully aligned, so I think we need to design
> > > a naming policy and document it.
> >
> > I agree that align this is a good idea. And for this reason I chosen to
> > update this patch as such:
> >
> > "%s output", dev_name(vin->dev)
>
> Wouldn't it be easier for userspace to use
>
> "VIN%u output", index
>
> where index is the VIN index as specified in DT ?

I would be OK whit this, but do this agree with the idea above that we
should try to align this name across drivers?

>
> > I hope this is a step in the correct direction. If not please let me
> > know as soon as possible so I can minimize the trouble for the other
> > developers doing stuff on-top of this series and there test scripts :-)
>
> --
> Regards,
>
> Laurent Pinchart
>

--
Regards,
Niklas Söderlund