Public bug reported:
Working version: Kernel 7.0.0-38-generic (all 3 external displays
function normally).
Broken version: Kernel 7.0.0-42-generic (external displays are
completely dark/undetected).
Hardware setup: Lenovo thinkbook 16p-g6-adr-16-amd-ryzen-9-8940hx-32-gb-ram
AMD Raphael iGPU + NVIDIA RTX 5060 (Lenovo device 8036).
1 display connected via HDMI, 2 displays connected via USB-C. No dock connected.
Relevant logs: lspci -k showed no active kernel driver for the NVIDIA
GPU under 7.0.0-42-generic, along with the DMCUB error entries visible
in dmesg.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-38-generic 7.0.0-38.38
ProcVersionSignature: Ubuntu 7.0.0-38.38-generic 7.0.14
Uname: Linux 7.0.0-38-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: lsbri 7674 F.... wireplumber
/dev/snd/controlC0: lsbri 7674 F.... wireplumber
/dev/snd/seq: lsbri 7666 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Thu Oct 29 00:57:46 2026
InstallationDate: Installed on 2026-05-01 (181 days ago)
InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
MachineType: LENOVO 21U0
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/home/username/.nix-profile/bin/zsh
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB:
0 amdgpudrmfb
1 nvidia-drmdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-38-generic
root=UUID=ac647a09-2a20-4524-b0d3-435d0e047bb2 ro quiet splash
amdgpu.dcdebugmask=0x10 amdgpu.aspm=0 pcie_aspm=off
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/14/2025
dmi.bios.release: 1.23
dmi.bios.vendor: LENOVO
dmi.bios.version: R7CN23WW
dmi.board.asset.tag: NO Asset Tag
dmi.board.name: LNVNB161216
dmi.board.vendor: LENOVO
dmi.board.version: SDK0T76528 WIN
dmi.chassis.asset.tag: NO Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: ThinkBook 16p G6 ADR
dmi.ec.firmware.release: 1.22
dmi.modalias:
dmi:bvnLENOVO:bvrR7CN23WW:bd08/14/2025:br1.23:efr1.22:svnLENOVO:pn21U0:pvrThinkBook16pG6ADR:rvnLENOVO:rnLNVNB161216:rvrSDK0T76528WIN:cvnLENOVO:ct10:cvrThinkBook16pG6ADR:skuLENOVO_MT_21U0_BU_idea_FM_ThinkBook16pG6ADR:pfaThinkBook16pG6ADR:
dmi.product.family: ThinkBook 16p G6 ADR
dmi.product.name: 21U0
dmi.product.sku: LENOVO_MT_21U0_BU_idea_FM_ThinkBook 16p G6 ADR
dmi.product.version: ThinkBook 16p G6 ADR
dmi.sys.vendor: LENOVO
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2172429
Title:
Regression: External displays fail on RTX 5060 / EVDI after upgrade
from 7.0.0-38 to 7.0.0-42
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