Re: [PATCH v10 3/6] media: uvcvideo: Quirk for invalid dev_sof in Logitech C922

From: Oleksandr Natalenko <oleksandr@natalenko.name>
To: Ricardo Ribalda <ribalda@chromium.org>
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>
Subject: Re: [PATCH v10 3/6] media: uvcvideo: Quirk for invalid dev_sof in Logitech C922
Date: Mon, 25 Mar 2024 10:23:00 +0100	[thread overview]
Message-ID: <12403186.O9o76ZdvQC@natalenko.name> (raw)
In-Reply-To: <CANiDSCsnOdTaW0Eg68+-niPXwPhYc3Br6cWoGiHytZrFOGmcZA@mail.gmail.com>

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Hello.

On pondělí 25. března 2024 8:52:57, CET Ricardo Ribalda wrote:
> 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 one, 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=1
> ```

```
$ 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 size 4147200
…
100 (4) [-] none 100 200717 B 212.919114 213.079004 33.727 fps ts mono/SoE
101 (5) [-] none 101 200889 B 213.003703 213.114996 11.822 fps ts mono/SoE
102 (6) [-] none 102 200926 B 213.035571 213.146999 31.379 fps ts mono/SoE
103 (7) [-] none 103 200839 B 213.067424 213.179003 31.394 fps ts mono/SoE
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/SoE
106 (2) [-] none 106 201013 B 213.352228 213.279005 33.496 fps ts mono/SoE
…
168 (0) [-] none 168 200914 B 215.183707 215.347066 33.676 fps ts mono/SoE
169 (1) [-] none 169 201141 B 215.271693 215.379066 11.365 fps ts mono/SoE
170 (2) [-] none 170 201005 B 215.303449 215.415057 31.490 fps ts mono/SoE
171 (3) [-] none 171 201195 B 215.335295 215.447062 31.401 fps ts mono/SoE
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/SoE
174 (6) [-] none 174 200698 B 215.616811 215.547063 33.582 fps ts mono/SoE
175 (7) [-] none 175 201290 B 215.646196 215.579075 34.031 fps ts mono/SoE
176 (0) [-] none 176 200807 B 215.675857 215.615073 33.714 fps ts mono/SoE
…
```

Does the above mean the webcam is affected?

Thank you.

> 
> 
> Thanks!
> 

-- 
Oleksandr Natalenko (post-factum)

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