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

Laurent Pinchart
2018-01-08T16:34:54Z

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 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