Public bug reported:
Fresh installed Kubuntu Ubuntu 26.04 LTS on Lenovo X1 Yoga
Expected behaviour: Screen brightness buttons and UI adjusts screen
brightness out of the box
Actual behaviour:
Pressing the buttons made the slider appear, but the backlight stayed
the same.
Working Fix:
I tried a bunch of different grub options, ended up with these for it to work:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=native
i915.enable_dpcd_backlight=0"
With the above GRUB settings, the buttons and the slider in the UI adjust the
screen brightness.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-30-generic 7.0.0-30.30
ProcVersionSignature: Ubuntu 7.0.0-30.30-generic 7.0.12
Uname: Linux 7.0.0-30-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: johny 1458 F.... wireplumber
/dev/snd/seq: johny 1455 F.... pipewire
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Wed Aug 26 21:56:11 2026
InstallationDate: Installed on 2026-08-21 (5 days ago)
InstallationMedia: Kubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423)
MachineType: LENOVO 20LD0016US
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-30-generic
root=UUID=7fec462a-883a-4cdd-9482-0be282d7256b ro rootflags=subvol=@ quiet
cryptdevice=UUID=e46eaf0b-da02-4a06-9470-a7c2247023a2:luks-e46eaf0b-da02-4a06-9470-a7c2247023a2
root=/dev/mapper/luks-e46eaf0b-da02-4a06-9470-a7c2247023a2 splash
acpi_backlight=native i915.enable_dpcd_backlight=0
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: 11/21/2024
dmi.bios.release: 1.55
dmi.bios.vendor: LENOVO
dmi.bios.version: N25ET69W (1.55 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20LD0016US
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 31
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.21
dmi.modalias:
dmi:bvnLENOVO:bvrN25ET69W(1.55):bd11/21/2024:br1.55:efr1.21:svnLENOVO:pn20LD0016US:pvrThinkPadX1Yoga3rd:rvnLENOVO:rn20LD0016US:rvrSDK0J40697WIN:cvnLENOVO:ct31:cvrNone:skuLENOVO_MT_20LD_BU_Think_FM_ThinkPadX1Yoga3rd:pfaThinkPadX1Yoga3rd:
dmi.product.family: ThinkPad X1 Yoga 3rd
dmi.product.name: 20LD0016US
dmi.product.sku: LENOVO_MT_20LD_BU_Think_FM_ThinkPad X1 Yoga 3rd
dmi.product.version: ThinkPad X1 Yoga 3rd
dmi.sys.vendor: LENOVO
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2165188
Title:
Lenovo X1 Yoga requires i915.enable_dpcd_backlight=0
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2165188/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
