Bug#1125881: linux-image-6.12.63+deb13-amd64: Hauppauge WinTV-Quad Capture Card (using cx23885 module) fails to acquire channel lock

[Salvatore Bonaccorso <carnil@debian.org>]

Contol: tags -1 + moreinfo upstream

On Sun, Jan 18, 2026 at 10:10:39AM -0600, Michael Frotscher wrote:
> Package: src:linux
> Version: 6.12.63-1
> Severity: normal
> X-Debbugs-Cc: debian-amd64@lists.debian.org
> User: debian-amd64@lists.debian.org
> Usertags: amd64
> 
> Dear Maintainer,
> 
>    * What led up to the situation? Kernel upgrade. No errors in boot log, card
> shows up in lspci and the appropriate devices in /dev, but card fails to
> acquire channel lock for any channel.
>    * What exactly did you do (or not do) that was effective (or
>      ineffective)? Booted previous stable kernel 6.12.57+deb13-amd64
>    * What was the outcome of this action? TV card works as expected
>    * What outcome did you expect instead? None

Thanks, as you can confirm the regreession from previous 6.12.57-1,
can you please bisect the changes to 6.12.63 to identify the breaking
commit? That would involve compiling and testing a few kernels:

    git clone --single-branch -b linux-6.12.y https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
    cd linux-stable
    git checkout v6.12.57
    cp /boot/config-$(uname -r) .config
    yes '' | make localmodconfig
    make savedefconfig
    mv defconfig arch/x86/configs/my_defconfig

    # test 6.12.57 to ensure this is "good"
    make my_defconfig
    make -j $(nproc) bindeb-pkg
    ... install the resulting .deb package and confirm the card works.

    # test 6.12.63 to ensure this is "bad"
    git checkout v6.12.63
    make my_defconfig
    make -j $(nproc) bindeb-pkg
    ... install the resulting .deb package and confirm the problem exists.

With that confirmed, the bisection can start:

    git bisect start
    git bisect good v6.12.57
    git bisect bad v6.12.63

In each bisection step git checks out a state between the oldest
known-bad and the newest known-good commit. In each step test using:

    make my_defconfig
    make -j $(nproc) bindeb-pkg
    ... install, verify the if problem exists.

and if the problem is hit run:

    git bisect bad

and if the problem doesn't trigger run:

    git bisect good

. Please pay attention to always select the just built kernel for
booting, it won't always be the default kernel picked up by grub.

Iterate until git announces to have identified the first bad commit.

Then provide the output of

    git bisect log

In the course of the bisection you might have to uninstall previous
kernels again to not exhaust the disk space in /boot. Also in the end
uninstall all self-built kernels again.

Regards,
Salvatore