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From: Ricardo Ribalda <ribalda@chromium.org>
Date: Mon, 25 Mar 2024 10:25:51 +0100
Message-ID: <CANiDSCuma7aGxq7T2uYMgn_JEW223LdR4as83UT2Aj3QmVu4ig@mail.gmail.com>
Subject: Re: [PATCH v10 3/6] media: uvcvideo: Quirk for invalid dev_sof in
 Logitech C922
To: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>, 
	Mauro Carvalho Chehab <mchehab@kernel.org>, linux-media@vger.kernel.org, 
	linux-kernel@vger.kernel.org, "hn.chen" <hn.chen@sunplusit.com>, 
	Hans Verkuil <hverkuil@xs4all.nl>, Sergey Senozhatsky <senozhatsky@chromium.org>
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Hi Oleksandr

On Mon, 25 Mar 2024 at 10:23, Oleksandr Natalenko
<oleksandr@natalenko.name> wrote:
>
> Hello.
>
> On pond=C4=9Bl=C3=AD 25. b=C5=99ezna 2024 8:52:57, CET Ricardo Ribalda wr=
ote:
> > Hi Oleksandr
> >
> > On Sat, 23 Mar 2024 at 13:16, Oleksandr Natalenko
> > <oleksandr@natalenko.name> wrote:
> >
> > >
> > > How do I check whether C920 (046d:082d) is affected too? I have got o=
ne, I can run tests on it as long as those will not blow the webcam up.
> > >
> > > Thanks.
> > >
> >
> > First of all you need to enable the hwtimestamps in the driver. You
> > could do that with
> >
> > ```
> > rmmod uvcvideo; modprobe uvcvideo hwtimestamps=3D1
> > ```
>
> ```
> $ cat /sys/module/uvcvideo/parameters/hwtimestamps
> 1
> ```
>
> > Then capture some frames with yavta
> > ```
> > yavta -c /dev/video0
> > ```
> >
> > After around 5 seconds all the frames should have a stable fps, the
> > fps is not stable then your camera is affected with this bug.
>
> ```
> $ ./yavta -c /dev/video1
> Device /dev/video1 opened.
> Device `HD Pro Webcam C920' on `usb-0000:0f:00.3-3.4' (driver 'uvcvideo')=
 supports video, capture, without mplanes.
> Video format: MJPEG (47504a4d) 1920x1080 (stride 0) field none buffer siz=
e 4147200
> =E2=80=A6
> 100 (4) [-] none 100 200717 B 212.919114 213.079004 33.727 fps ts mono/So=
E
> 101 (5) [-] none 101 200889 B 213.003703 213.114996 11.822 fps ts mono/So=
E
> 102 (6) [-] none 102 200926 B 213.035571 213.146999 31.379 fps ts mono/So=
E
> 103 (7) [-] none 103 200839 B 213.067424 213.179003 31.394 fps ts mono/So=
E
> 104 (0) [-] none 104 200692 B 213.293180 213.214991 4.430 fps ts mono/SoE
> 105 (1) [-] none 105 200937 B 213.322374 213.247001 34.254 fps ts mono/So=
E
> 106 (2) [-] none 106 201013 B 213.352228 213.279005 33.496 fps ts mono/So=
E
> =E2=80=A6
> 168 (0) [-] none 168 200914 B 215.183707 215.347066 33.676 fps ts mono/So=
E
> 169 (1) [-] none 169 201141 B 215.271693 215.379066 11.365 fps ts mono/So=
E
> 170 (2) [-] none 170 201005 B 215.303449 215.415057 31.490 fps ts mono/So=
E
> 171 (3) [-] none 171 201195 B 215.335295 215.447062 31.401 fps ts mono/So=
E
> 172 (4) [-] none 172 200933 B 215.557731 215.479072 4.496 fps ts mono/SoE
> 173 (5) [-] none 173 200973 B 215.587033 215.515063 34.127 fps ts mono/So=
E
> 174 (6) [-] none 174 200698 B 215.616811 215.547063 33.582 fps ts mono/So=
E
> 175 (7) [-] none 175 201290 B 215.646196 215.579075 34.031 fps ts mono/So=
E
> 176 (0) [-] none 176 200807 B 215.675857 215.615073 33.714 fps ts mono/So=
E
> =E2=80=A6
> ```
>
> Does the above mean the webcam is affected?

Looks like it.... could you try applying this patch and run with

rmmod uvcvideo; modprobe uvcvideo hwtimestamps=3D1 quirks=3D0x4000

to see if that fixes it for you?

Thanks!

>
> Thank you.
>
> >
> >
> > Thanks!
> >
>
>
> --
> Oleksandr Natalenko (post-factum)


--=20
Ricardo Ribalda