Public bug reported:
The internal display brightness/backlight control on my Lenovo Thinkpad
T460s does not work correctly when running kernel 7.0.0-28-generic.
The brightness controls are present and the system expoes
intel_backlight, but changing the brightness value/ using the brightness
keys does not actually change the brightness of the internal display.
booting the same system with kernel 6.8.0-137-generic fixes the problem
completely and brightness works normally.
Hardware: Lenovo ThinkPad T460s, intel HD graphics 520 (I915)
I also tried acpi_backlight=native, but this did not fix it.
This appears to be a regression between kernel 6.8 and 7.0.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-7.0.0-28-generic 7.0.0-28.28~24.04.1
ProcVersionSignature: Ubuntu 7.0.0-28.28~24.04.1-generic 7.0.12
Uname: Linux 7.0.0-28-generic x86_64
ApportVersion: 2.28.3-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: stefanos-kapa 2187 F.... wireplumber
/dev/snd/seq: stefanos-kapa 2181 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sun Aug 16 10:43:39 2026
InstallationDate: Installed on 2026-08-14 (2 days ago)
InstallationMedia: Ubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
Lsusb:
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:0a2b Intel Corp. Bluetooth wireless interface
Bus 001 Device 003: ID 04f2:b52c Chicony Electronics Co., Ltd Integrated Camera
Bus 001 Device 004: ID 138a:0090 Validity Sensors, Inc. VFS7500 Touch
Fingerprint Sensor
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
MachineType: LENOVO 20FA0046MN
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-28-generic
root=/dev/mapper/ubuntu--vg-ubuntu--lv ro quiet splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-7.0.0-28-generic N/A
linux-backports-modules-7.0.0-28-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.29
SourcePackage: linux-hwe-7.0
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/15/2022
dmi.bios.release: 1.58
dmi.bios.vendor: LENOVO
dmi.bios.version: N1CET90W (1.58 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20FA0046MN
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.14
dmi.modalias:
dmi:bvnLENOVO:bvrN1CET90W(1.58):bd11/15/2022:br1.58:efr1.14:svnLENOVO:pn20FA0046MN:pvrThinkPadT460s:rvnLENOVO:rn20FA0046MN:rvrNotDefined:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20FA_BU_Think_FM_ThinkPadT460s:pfaThinkPadT460s:
dmi.product.family: ThinkPad T460s
dmi.product.name: 20FA0046MN
dmi.product.sku: LENOVO_MT_20FA_BU_Think_FM_ThinkPad T460s
dmi.product.version: ThinkPad T460s
dmi.sys.vendor: LENOVO
** Affects: linux-hwe-7.0 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
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https://bugs.launchpad.net/bugs/2163593
Title:
ThinkPad T460s internal display backlight does not work with linux 7.0
kernel, works with 6.8
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