Re: [PATCH v3 7/8] media: uvcvideo: Set a different name for the metadata entity

[Ricardo Ribalda Delgado]

HI Laurent

Thanks for the review

On Fri, Mar 12, 2021 at 11:30 PM Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
> On Fri, Mar 12, 2021 at 01:48:29PM +0100, Ricardo Ribalda wrote:
> > All the entities must have a unique name. And now that we are at it, we
> > append the entity->id to the name to avoid collisions on multi-chain
> > devices.
> >
> > Fixes v4l2-compliance:
> > Media Controller ioctls:
> >                 fail: v4l2-test-media.cpp(205): v2_entity_names_set.find(key) != v2_entity_names_set.end()
> >         test MEDIA_IOC_G_TOPOLOGY: FAIL
> >                 fail: v4l2-test-media.cpp(394): num_data_links != num_links
> >       test MEDIA_IOC_ENUM_ENTITIES/LINKS: FAIL
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
> > ---
> >  drivers/media/usb/uvc/uvc_driver.c | 21 ++++++++++++++++++++-
> >  1 file changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index 35873cf2773d..6c928e708615 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -2154,6 +2154,18 @@ static void uvc_unregister_video(struct uvc_device *dev)
> >  #endif
> >  }
> >
> > +static int uvc_oterm_id(struct uvc_video_chain *chain)
> > +{
> > +     struct uvc_entity *entity;
> > +
> > +     list_for_each_entry(entity, &chain->entities, chain) {
> > +             if (UVC_ENTITY_IS_OTERM(entity))
> > +                     return entity->id;
>
> It can also be an ITERM for output devices. You can drop this function
> and use stream>header.bTerminalLink below (see uvc_stream_by_id() and
> its usage in uvc_register_terms()).
>
> > +     }
> > +
> > +     return -1;
> > +}
> > +
> >  int uvc_register_video_device(struct uvc_device *dev,
> >                             struct uvc_streaming *stream,
> >                             struct video_device *vdev,
> > @@ -2162,6 +2174,8 @@ int uvc_register_video_device(struct uvc_device *dev,
> >                             const struct v4l2_file_operations *fops,
> >                             const struct v4l2_ioctl_ops *ioctl_ops)
> >  {
> > +     char prefix[sizeof(vdev->name) - 9];
> > +     const char *suffix;
> >       int ret;
> >
> >       /* Initialize the video buffers queue. */
> > @@ -2190,16 +2204,21 @@ int uvc_register_video_device(struct uvc_device *dev,
> >       case V4L2_BUF_TYPE_VIDEO_CAPTURE:
> >       default:
> >               vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
> > +             suffix = "video";
> >               break;
> >       case V4L2_BUF_TYPE_VIDEO_OUTPUT:
> >               vdev->device_caps = V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_STREAMING;
> > +             suffix = "out";
>
> I wonder if these two should be video-cap and video-out (or vid-cap and
> vid-out if you want to shorten them) ?
>
> >               break;
> >       case V4L2_BUF_TYPE_META_CAPTURE:
> >               vdev->device_caps = V4L2_CAP_META_CAPTURE | V4L2_CAP_STREAMING;
> > +             suffix = "meta";
> >               break;
> >       }
> >
> > -     strscpy(vdev->name, dev->name, sizeof(vdev->name));
> > +     strscpy(prefix, dev->name, sizeof(prefix));
> > +     snprintf(vdev->name, sizeof(vdev->name), "%s-%d %s", prefix,
>
> The unit ID is never negative, so %u ?
>
> > +              uvc_oterm_id(stream->chain), suffix);
>
> Truncating the device name at the beginning of the video node name isn't
> very nice :-S How about the following ?
>
>         snprintf(vdev->name, sizeof(vdev->name), "%s-%u (%s)", type_name,
>                  uvc_oterm_id(stream->chain), dev->name);
>
> with the suffix variable renamed to type_name ?
>
> Thinking some more about it, vdev->name serves two purposes in the
> driver: creating the entity name, and reporting the card name in
> querycap. The former is done in the V4L2 core, which uses vdev->name
> as-is. In this context, we con't need to add dev->name, it would be
> redundant as the media controller device already reports it. The latter
> is done in uvc_ioctl_querycap(). How about dropping dev->name from
> vdev->name, and modifying uvc_ioctl_querycap() to use dev->name instead
> of cap->card ?
>

Something like ?
https://git.kernel.org/pub/scm/linux/kernel/git/ribalda/linux.git/commit/?h=uvc-compliance-v4&id=d4f7363455837116268152c96bf4b78d9761ad1e
https://git.kernel.org/pub/scm/linux/kernel/git/ribalda/linux.git/commit/?h=uvc-compliance-v4&id=ee3916f12b30f56c03d5622ba8a599b9c610a055

I need to work on the V4L2_CTRL_FLAG_GRABBED issue and then I will
send the whole v4 series that can pass all the v4l2-compliance test :)

Thanks!

> >
> >       /*
> >        * Set the driver data before calling video_register_device, otherwise
>
> --
> Regards,
>
> Laurent Pinchart



-- 
Ricardo Ribalda