Re: [PATCH] media: usb: uvc: fill in description for unknown pixelformats

[Ricardo Ribalda <ribalda@chromium.org>]

Hi Hans

Thanks for the patch.

I believe the user can fetch this info from lsusb, so this is kind of
duplicated info, and this is why it was removed.

Is there an app that uses this unknown format code ? Or the only
complaint is that WARN() is too loud for the user?

Regards!

On Wed, 29 Mar 2023 at 14:39, Hans Verkuil <hverkuil@xs4all.nl> wrote:
>
> If the fcc is 0 (indicating an unknown GUID format), then fill in the
> description field in ENUM_FMT. Otherwise the V4L2 core will WARN.
>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Fixes: 50459f103edf ("media: uvcvideo: Remove format descriptions")
> ---
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index 7aefa76a42b3..2f1ced1212cd 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -256,6 +256,9 @@ static int uvc_parse_format(struct uvc_device *dev,
>                 } else {
>                         dev_info(&streaming->intf->dev,
>                                  "Unknown video format %pUl\n", &buffer[5]);
> +                       snprintf(format->name, sizeof(format->name), "%pUl\n",
> +                                &buffer[5]);
Don't we need at least 38 chars for this?

https://docs.kernel.org/core-api/printk-formats.html#uuid-guid-addresses


> +
>                         format->fcc = 0;
>                 }
>
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 35453f81c1d9..fc6f9e7d8506 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -713,6 +713,10 @@ static int uvc_ioctl_enum_fmt(struct uvc_streaming *stream,
>         if (format->flags & UVC_FMT_FLAG_COMPRESSED)
>                 fmt->flags |= V4L2_FMT_FLAG_COMPRESSED;
>         fmt->pixelformat = format->fcc;
> +       if (format->name[0])
> +               strscpy(fmt->description, format->name,
> +                       sizeof(fmt->description));
> +
>         return 0;
>  }
>
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 9a596c8d894a..22656755a801 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -264,6 +264,8 @@ struct uvc_format {
>         u32 fcc;
>         u32 flags;
>
> +       char name[32];
> +
>         unsigned int nframes;
>         struct uvc_frame *frame;
>  };
>


--
Ricardo Ribalda