Control: tags -1 + moreinfo upstream
On Sun, Jun 28, 2026 at 02:45:36AM +0200, dado wrote:
> Source: linux
> Version: 6.12.94-1
> Severity: important
> X-Debbugs-Cc: [email protected]
>
> Dear Maintainer,
>
> Thunderbolt 4 dock stops working completely after upgrading from
> 6.12.90+deb13.1-amd64 to 6.12.94+deb13-amd64. The dock is detected
> and authorized by bolt but all tunnel creation fails, making peripherals
> and laptop charging unavailable. A similar issue has occurred on
> previous kernel upgrades on this machine.
>
> == Hardware ==
>
> Machine: Lenovo ThinkPad T16 Gen 4 (21QN001MSC)
> CPU: AMD Ryzen AI 7 PRO 350 w/ Radeon 860M
> TB controller: Intel Thunderbolt 4 Goshen Ridge [8086:0b26] rev 03
> (PCI 61:00.0 / 62:00.0-04.0)
> Dock: Lenovo ThinkPad Thunderbolt 4 Smart Dock Gen 2 7500
> (vendor=0x108 device=0x2350)
>
> == Regression range ==
>
> Last working kernel: 6.12.90+deb13.1-amd64
> First broken kernel: 6.12.94+deb13-amd64
Since you reliably can reproduce the issue and regression, can you
please bisect the changes between 6.12.90 and 6.12.94 upstream to
identify the breaking commit. This will involve compiling and testing
a couple of 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 v6.12.90
cp /boot/config-$(uname -r) .config
yes '' | make localmodconfig
make savedefconfig
mv defconfig arch/x86/configs/my_defconfig
# test 6.12.90 to ensure this is "good"
make my_defconfig
make -j $(nproc) bindeb-pkg
... install the resulting .deb package and confirm problem does not exist
# test 6.12.94 to ensure this is "bad"
git checkout v6.12.35
make my_defconfig
make -j $(nproc) bindeb-pkg
... install the resulting .deb package and confirm problem exists
With that confirmed, the bisection can start:
git bisect start
git bisect good v6.12.90
git bisect bad v6.12.94
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 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
