Bug#1121718: linux-image-6.17.8+deb14-amd64: Logitech C920 HD Pro Webcam shows flickering artifacts (sometimes)
Control: tags -1 + moreinfo
Hi Ralf,
On Mon, Dec 01, 2025 at 10:34:52AM +0100, Ralf Jung wrote:
> Package: src:linux
> Version: 6.17.8-1
> Severity: normal
> X-Debbugs-Cc: debian-amd64@lists.debian.org
> User: debian-amd64@lists.debian.org
> Usertags: amd64
>
> Dear Maintainer,
>
> Since a recent kernel update, my webcam stopped working properly. The webcam
> model is "Logitech C920 HD Pro" (USB ID 046d:0892); I will put the full lsusb
> output below. What happens is that, when I am in a Zoom call, after someone else
> joins the call, flickering artifacts start to appear: the bottom half of the
> image turns gray. I will attach an image. I have so far not been able to
> reproduce this outside of Zoom. I tried Jitsi in the browser and Gnome Cheese.
> (Zoom does *something* with the webcam when someone joins the call: the exact
> frame of the webcam, i.e. how much of the room I see and where the image cuts
> off, changes. I have no idea what that is about.)
>
> I tried playing around with power_line_frequency; that did not help at all.
>
> This only started recently. I tried booting a 6.12 kernel (with the same
> userspace), that fixed the issue -- so it very much looks like a kernel issue to
> me. The issue is also present in 6.16, so it's a regression introduced some time
> between 6.12 and 6.16. I use Zoom fairly regularly professionally, so this bug
> means I am pretty much stuck with a 6.12 kernel for now.
If you reliably can reproduce the issue then (although I realize that
each testing step is time consuming), I would suggest to start a
bisect.
First though narrow down more closely the Debian versions which expose
the problen and not (using the images fetched from
https://snapshot.debian.org/). Once you have two upstream versions
close enough, start a bisect.
Do you need instructions/help on how to do that?
Regards,
Salvatore
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