Public bug reported:
Changing internal display brightness with keyboard buttons or software
slider does not work with kernel 7.0.0-28 and later. GUI responds
correctly and shows OSD slider but with no effect on actual brightness.
Reverting to 7.0.0-27 completely resolves the issue.
Operating System: Kubuntu 26.04 LTS
KDE Plasma Version: 6.6.6
KDE Frameworks Version: 6.24.0
Qt Version: 6.10.2
Kernel Version: 7.0.0-29-generic (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i5-8250U CPU @ 1.60GHz
Memory: 16 GiB of RAM (15,4 GiB usable)
Graphics Processor: Intel® UHD Graphics 620
Manufacturer: LENOVO
Product Name: 20LS001APB
System Version: ThinkPad L480
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-29-generic 7.0.0-29.29
ProcVersionSignature: Ubuntu 7.0.0-29.29-generic 7.0.12
Uname: Linux 7.0.0-29-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: adrian 1683 F.... wireplumber
/dev/snd/seq: adrian 1679 F.... pipewire
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Sun Aug 16 20:50:25 2026
InstallationDate: Installed on 2026-07-12 (35 days ago)
InstallationMedia: Kubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423)
Lsusb:
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 1038:184d SteelSeries ApS SteelSeries Prime Mini
Bus 001 Device 004: ID 5986:2113 Bison Electronics Inc. SunplusIT Integrated
Camera
Bus 001 Device 005: ID 06cb:009a Synaptics, Inc. Metallica MIS Touch
Fingerprint Reader
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
MachineType: LENOVO 20LS001APB
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-29-generic
root=UUID=3bf2d49d-799f-4ae6-b0de-64e14314f483 ro quiet
cryptdevice=UUID=8cd4aa2b-6444-46ce-8ebb-1a320b5b0ad1:luks-8cd4aa2b-6444-46ce-8ebb-1a320b5b0ad1
root=/dev/mapper/luks-8cd4aa2b-6444-46ce-8ebb-1a320b5b0ad1 splash
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/03/2023
dmi.bios.release: 1.46
dmi.bios.vendor: LENOVO
dmi.bios.version: R0QET69W (1.46 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20LS001APB
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.46
dmi.modalias:
dmi:bvnLENOVO:bvrR0QET69W(1.46):bd01/03/2023:br1.46:efr1.46:svnLENOVO:pn20LS001APB:pvrThinkPadL480:rvnLENOVO:rn20LS001APB:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20LS_BU_Think_FM_ThinkPadL480:pfaThinkPadL480:
dmi.product.family: ThinkPad L480
dmi.product.name: 20LS001APB
dmi.product.sku: LENOVO_MT_20LS_BU_Think_FM_ThinkPad L480
dmi.product.version: ThinkPad L480
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/2163611
Title:
ThinkPad L480 internal display backlight control does not work with
>=7.0.0-28 kernel, works with 7.0.0-27
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