Em Thu, 25 Sep 2014 15:59:12 +0200 Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx> escreveu: > > Am 24.09.2014 um 01:18 schrieb Mauro Carvalho Chehab: > > Em Tue, 23 Sep 2014 21:32:02 +0200 > > Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx> escreveu: > > > >> 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@xxxxxxxxxxxxxxx> > >>> > >>> 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. > > Why Dangerous? > You are an experienced kernel developer. If you still fail to see that > after so many years, sorry, I can't help you. > > > Did you identify any problem? > Yes I've identified a potential problem. > Read it again, it's in the line you skipped in this reply. Did you read the video_ioctl_ops struct? See: .vidioc_g_fmt_vid_cap = vidioc_g_fmt_vid_cap, .vidioc_try_fmt_vid_cap = vidioc_try_fmt_vid_cap, .vidioc_s_fmt_vid_cap = vidioc_s_fmt_vid_cap, .vidioc_g_fmt_vbi_cap = vidioc_g_fmt_vbi_cap, .vidioc_try_fmt_vbi_cap = vidioc_g_fmt_vbi_cap, .vidioc_s_fmt_vbi_cap = vidioc_g_fmt_vbi_cap, .vidioc_enum_framesizes = vidioc_enum_framesizes, .vidioc_g_audio = vidioc_g_audio, .vidioc_s_audio = vidioc_s_audio, Only the video node calls s_fmt_vid_cap. There's nothing to be set for VBI. In other words, a call to VIDIOC_S_FMT will actually call vidioc_g_fmt_vbi_cap() if called from VBI. So, I was unable to see any potencial issues. > > With what application? > I would be willing to spend more time on this and test this critical > patch (like I already did in the past). > But I don't have access to analog TV here at the moment, sorry. It would > have to wait ~2 weeks. On my tests with the 3 existing VBI apps, they all worked fine after the patch, no matter if the VBI or the video application is started first. That's why I asked. Regards, Mauro -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
