Status changed to 'Confirmed' because the bug affects multiple users.
** Changed in: linux-signed-hwe-6.8 (Ubuntu)
Status: New => Confirmed
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https://bugs.launchpad.net/bugs/2094733
Title:
External monitor not working after kernel update to 6.8.0-51 on Ubuntu
22.04 (DisplayPort over USB-C)
Status in linux-signed-hwe-6.8 package in Ubuntu:
Confirmed
Bug description:
After upgrading the Linux kernel to version 6.8.0-51 on Ubuntu 22.04,
the external monitor connected via DisplayPort through a docking
station over USB-C stopped functioning. The monitor is no longer
detected by the system, and no output is displayed. However, when
connecting the same monitor via HDMI, it works as expected.
Steps to Reproduce:
Update the kernel to version 6.8.0-51 using unattended-upgrades or manual
installation.
Connect a docking station to the laptop via USB-C.
Connect an external monitor to the docking station via DisplayPort.
Check if the monitor is detected in the display settings or xrandr.
Expected Behavior:
The external monitor connected via the docking station using DisplayPort
should be detected and function correctly, as it did in the previous kernel
version 6.8.0-50.
Observed Behavior:
The monitor connected via DisplayPort through the docking station is not
detected, and no output is displayed.
Connecting the monitor via HDMI directly or through the docking station works
as expected.
Additional Information:
Kernel version: 6.8.0-51 (affected), 6.8.0-50 (working).
Ubuntu version: Ubuntu 22.04.5 LTS.
Docking Station: Lenovo ThinkPad USB-C Dock, Type 40A9
Connection setup: Laptop → USB-C → Docking Station → DisplayPort → Monitor.
Workaround:
Reverting to kernel version 6.8.0-50 resolves the issue, and the monitor
functions as expected when connected via DisplayPort through the docking
station.
ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: linux-image-6.8.0-51-generic (not installed)
ProcVersionSignature: Ubuntu 6.8.0-50.51~22.04.1-generic 6.8.12
Uname: Linux 6.8.0-50-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.6
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Tue Jan 14 08:51:54 2025
InstallationDate: Installed on 2024-05-13 (246 days ago)
InstallationMedia: Ubuntu 22.04.3 LTS "Jammy Jellyfish" - Release amd64
(20230807.2)
SourcePackage: linux-signed-hwe-6.8
UpgradeStatus: No upgrade log present (probably fresh install)
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