apport information
** Tags added: apport-collected resolute
** Description changed:
ystem:
Ubuntu 26.04.1
Lenovo ThinkPad T14 Gen 5 Intel
Affected kernel: 7.0.0-38-generic
Working kernel: 7.0.0-34-generic
Description:
After upgrading the kernel from 7.0.0-34-generic to 7.0.0-38-generic,
screen brightness control stopped working. The display remains at
maximum brightness.
Both the keyboard brightness hotkeys and the GNOME Settings brightness
slider have no effect.
Steps to reproduce:
Boot Ubuntu 26.04.1 with kernel 7.0.0-38-generic.
Try to change screen brightness using the keyboard hotkeys.
Observe that the display brightness remains at maximum.
Reboot using kernel 7.0.0-34-generic.
Verify that brightness control works again.
Expected result: Screen brightness can be adjusted using the keyboard
hotkeys.
Actual result: Brightness is stuck at maximum with kernel
7.0.0-38-generic.
- This appears to be a kernel regression. The issue is reproducible on
- this hardware and disappears when booting the previous kernel.
+ This appears to be a kernel regression. The issue is reproducible on this
hardware and disappears when booting the previous kernel.
+ ---
+ ProblemType: Bug
+ ApportVersion: 2.34.1-0ubuntu0.1
+ Architecture: amd64
+ AudioDevicesInUse:
+ USER PID ACCESS COMMAND
+ /dev/snd/seq: lesha 3788 F.... pipewire
+ CasperMD5CheckResult: pass
+ CurrentDesktop: ubuntu:GNOME
+ DistroRelease: Ubuntu 26.04
+ InstallationDate: Installed on 2026-04-25 (173 days ago)
+ InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64
(20260423.1)
+ MachineType: LENOVO 21ML0023RA
+ Package: linux (not installed)
+ ProcFB: 0 simpledrmdrmfb
+ ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-38-generic
root=UUID=b11114a3-0b0e-4203-8349-561c1a71f4af ro quiet splash
usb-storage.quirks=152d:a580:u
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
+ ProcVersionSignature: Ubuntu 7.0.0-38.38-generic 7.0.14
+ Tags: resolute
+ Uname: Linux 7.0.0-38-generic x86_64
+ UpgradeStatus: No upgrade log present (probably fresh install)
+ UserGroups: N/A
+ _MarkForUpload: True
+ dmi.bios.date: 04/23/2026
+ dmi.bios.release: 1.18
+ dmi.bios.vendor: LENOVO
+ dmi.bios.version: N47ET29W (1.18 )
+ dmi.board.asset.tag: Not Available
+ dmi.board.name: 21ML0023RA
+ dmi.board.vendor: LENOVO
+ dmi.board.version: SDK0T76530 WIN
+ dmi.chassis.asset.tag: No Asset Information
+ dmi.chassis.type: 10
+ dmi.chassis.vendor: LENOVO
+ dmi.chassis.version: None
+ dmi.ec.firmware.release: 1.16
+ dmi.modalias:
dmi:bvnLENOVO:bvrN47ET29W(1.18):bd04/23/2026:br1.18:efr1.16:svnLENOVO:pn21ML0023RA:pvrThinkPadT14Gen5:rvnLENOVO:rn21ML0023RA:rvrSDK0T76530WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_21ML_BU_Think_FM_ThinkPadT14Gen5:pfaThinkPadT14Gen5:
+ dmi.product.family: ThinkPad T14 Gen 5
+ dmi.product.name: 21ML0023RA
+ dmi.product.sku: LENOVO_MT_21ML_BU_Think_FM_ThinkPad T14 Gen 5
+ dmi.product.version: ThinkPad T14 Gen 5
+ dmi.sys.vendor: LENOVO
** Attachment added: "AlsaInfo.txt"
https://bugs.launchpad.net/bugs/2170625/+attachment/6009465/+files/AlsaInfo.txt
--
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https://bugs.launchpad.net/bugs/2170625
Title:
[REGRESSION] Screen brightness stuck at 100% on Lenovo ThinkPad T14
Gen 5 Intel with kernel 7.0.0-38-generic
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