Re: [PATCH 2/2] em28xx: fix VBI handling logic

["Frank Schäfer" <fschaefer.oss@googlemail.com>]

Am 19.09.2014 um 18:02 schrieb Mauro Carvalho Chehab:
> When both VBI and video are streaming, and video stream is stopped,
> a subsequent trial to restart it will fail, because S_FMT will
> return -EBUSY.
>
> That prevents applications like zvbi to work properly.
>
> Please notice that, while this fix it fully for zvbi, the
> best is to get rid of streaming_users and res_get logic as a hole.
>
> However, this single-line patch is better to be merged at -stable.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
>
> diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
> index 08569cbccd95..d75e7f82dfb9 100644
> --- a/drivers/media/usb/em28xx/em28xx-video.c
> +++ b/drivers/media/usb/em28xx/em28xx-video.c
> @@ -1351,7 +1351,7 @@ static int vidioc_s_fmt_vid_cap(struct file *file, void *priv,
>  	struct em28xx *dev = video_drvdata(file);
>  	struct em28xx_v4l2 *v4l2 = dev->v4l2;
>  
> -	if (v4l2->streaming_users > 0)
> +	if (vb2_is_busy(&v4l2->vb_vidq))
Looks dangerous.
Are you 100% sure that VIDIOC_S_FMT can have no effect on VBI capturing ?
It seems to trigger writes to multiple registers...

Regards,
Frank

>  		return -EBUSY;
>  
>  	vidioc_try_fmt_vid_cap(file, priv, f);