Public bug reported:
After upgrading to kernel version 6.17.0-23-generic, my dual monitor
setup connected via a ThinkPad Universal Thunderbolt 4 Smart Dock (40B1)
stopped working. The monitors are not detected by xrandr, although USB
peripherals (keyboard/mouse) connected to the same dock continue to work
perfectly.
Regression:
* Works: Kernel 6.17.0-22-generic and older (e.g., 6.14.x).
* Fails: Kernel 6.17.0-23-generic.
System Info:
* Hardware: Laptop with Intel Meteor Lake Graphics (no dedicated NVIDIA GPU).
* Dock: Lenovo ThinkPad Universal Thunderbolt 4 Smart Dock.
* Connection: boltctl shows the dock as "authorized" with 40 Gb/s, but no
DisplayPort tunnels seem to be established for the video signal in the new
kernel.
Steps to reproduce:
* Boot into kernel 6.17.0-23.
* Connect the Thunderbolt 4 dock.
* Observe that mouse/keyboard work, but xrandr --listmonitors only shows the
internal laptop display.
* Reboot into kernel 6.17.0-22 -> monitors work immediately.
Note on accessibility: Please be aware that this is a workplace setup. I
will have limited access to this specific hardware (the dock and
monitors) over the next few weeks. I've provided all the logs I could
gather while the issue was occurring, but I might not be able to run
immediate follow-up tests on this specific setup for a while.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-22-generic 6.17.0-22.22~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-22.22~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-22-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: andreas 4814 F.... wireplumber
/dev/snd/controlC1: andreas 4814 F.... wireplumber
/dev/snd/seq: andreas 4807 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: GNOME
Date: Mon May 11 09:45:14 2026
InstallationDate: Installed on 2025-04-17 (389 days ago)
InstallationMedia: Ubuntu 24.04.2 LTS "Noble Numbat" - Release amd64 (20250215)
MachineType: Dell Inc. Latitude 5550
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-6.17.0-22-generic
root=/dev/mapper/ubuntu--vg-ubuntu--lv ro quiet splash vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-6.17.0-22-generic N/A
linux-backports-modules-6.17.0-22-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.26
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/12/2025
dmi.bios.release: 1.19
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.19.1
dmi.board.name: 0MMGXX
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.ec.firmware.release: 1.21
dmi.modalias:
dmi:bvnDellInc.:bvr1.19.1:bd12/12/2025:br1.19:efr1.21:svnDellInc.:pnLatitude5550:pvr:rvnDellInc.:rn0MMGXX:rvrA00:cvnDellInc.:ct10:cvr:sku0CB9:
dmi.product.family: Latitude
dmi.product.name: Latitude 5550
dmi.product.sku: 0CB9
dmi.sys.vendor: Dell Inc.
** Affects: linux-hwe-6.17 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
** Description changed:
After upgrading to kernel version 6.17.0-23-generic, my dual monitor
setup connected via a ThinkPad Universal Thunderbolt 4 Smart Dock (40B1)
stopped working. The monitors are not detected by xrandr, although USB
peripherals (keyboard/mouse) connected to the same dock continue to work
perfectly.
Regression:
- * Works: Kernel 6.17.0-22-generic and older (e.g., 6.14.x).
- * Fails: Kernel 6.17.0-23-generic.
+ * Works: Kernel 6.17.0-22-generic and older (e.g., 6.14.x).
+ * Fails: Kernel 6.17.0-23-generic.
System Info:
- * Hardware: Laptop with Intel Meteor Lake Graphics (no dedicated NVIDIA GPU).
- * Dock: Lenovo ThinkPad Universal Thunderbolt 4 Smart Dock.
- * Connection: boltctl shows the dock as "authorized" with 40 Gb/s, but no
DisplayPort tunnels seem to be established for the video signal in the new
kernel.
+ * Hardware: Laptop with Intel Meteor Lake Graphics (no dedicated NVIDIA GPU).
+ * Dock: Lenovo ThinkPad Universal Thunderbolt 4 Smart Dock.
+ * Connection: boltctl shows the dock as "authorized" with 40 Gb/s, but no
DisplayPort tunnels seem to be established for the video signal in the new
kernel.
Steps to reproduce:
- * Boot into kernel 6.17.0-23.
- * Connect the Thunderbolt 4 dock.
- * Observe that mouse/keyboard work, but xrandr --listmonitors only shows the
internal laptop display.
- * Reboot into kernel 6.17.0-22 -> monitors work immediately.
+ * Boot into kernel 6.17.0-23.
+ * Connect the Thunderbolt 4 dock.
+ * Observe that mouse/keyboard work, but xrandr --listmonitors only shows the
internal laptop display.
+ * Reboot into kernel 6.17.0-22 -> monitors work immediately.
+
+ Note on accessibility: Please be aware that this is a workplace setup. I
+ will have limited access to this specific hardware (the dock and
+ monitors) over the next few weeks. I've provided all the logs I could
+ gather while the issue was occurring, but I might not be able to run
+ immediate follow-up tests on this specific setup for a while.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-22-generic 6.17.0-22.22~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-22.22~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-22-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
- USER PID ACCESS COMMAND
- /dev/snd/controlC0: andreas 4814 F.... wireplumber
- /dev/snd/controlC1: andreas 4814 F.... wireplumber
- /dev/snd/seq: andreas 4807 F.... pipewire
+ USER PID ACCESS COMMAND
+ /dev/snd/controlC0: andreas 4814 F.... wireplumber
+ /dev/snd/controlC1: andreas 4814 F.... wireplumber
+ /dev/snd/seq: andreas 4807 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: GNOME
Date: Mon May 11 09:45:14 2026
InstallationDate: Installed on 2025-04-17 (389 days ago)
InstallationMedia: Ubuntu 24.04.2 LTS "Noble Numbat" - Release amd64
(20250215)
MachineType: Dell Inc. Latitude 5550
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-6.17.0-22-generic
root=/dev/mapper/ubuntu--vg-ubuntu--lv ro quiet splash vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
- linux-restricted-modules-6.17.0-22-generic N/A
- linux-backports-modules-6.17.0-22-generic N/A
- linux-firmware 20240318.git3b128b60-0ubuntu2.26
+ linux-restricted-modules-6.17.0-22-generic N/A
+ linux-backports-modules-6.17.0-22-generic N/A
+ linux-firmware 20240318.git3b128b60-0ubuntu2.26
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/12/2025
dmi.bios.release: 1.19
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.19.1
dmi.board.name: 0MMGXX
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.ec.firmware.release: 1.21
dmi.modalias:
dmi:bvnDellInc.:bvr1.19.1:bd12/12/2025:br1.19:efr1.21:svnDellInc.:pnLatitude5550:pvr:rvnDellInc.:rn0MMGXX:rvrA00:cvnDellInc.:ct10:cvr:sku0CB9:
dmi.product.family: Latitude
dmi.product.name: Latitude 5550
dmi.product.sku: 0CB9
dmi.sys.vendor: Dell Inc.
--
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https://bugs.launchpad.net/bugs/2152166
Title:
Dual monitors on ThinkPad Thunderbolt 4 Dock (40B1) not detected since
Kernel 6.17.0-23
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