Public bug reported:
The brightness slider in the system settings is either grayed out,
missing, or does not move at all when clicked/dragged.
The dedicated function keys (e.g., Fn+F5 / Fn+F6) do not trigger the on-
screen brightness pop-up (the system does not register the keypress as a
brightness command).
The screen is stuck at a single brightness level (usually 100%).
Adjusting brightness via the terminal using xrandr does work (software
brightness), proving the display is fine, but the hardware backlight
control is broken.
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/seq: ordo-chao 3027 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Aug 14 13:11:18 2026
InstallationDate: Installed on 2024-07-16 (759 days ago)
InstallationMedia: Ubuntu 24.04 LTS "Noble Numbat" - Release amd64 (20240424)
MachineType: HP HP EliteBook 840 G4
ProcFB: 0 simpledrmdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-28-generic
root=UUID=7496a204-db65-4c23-a6cf-b8de4f5b39c2 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: 12/29/2020
dmi.bios.release: 1.38
dmi.bios.vendor: HP
dmi.bios.version: P78 Ver. 01.38
dmi.board.name: 828C
dmi.board.vendor: HP
dmi.board.version: KBC Version 45.52
dmi.chassis.type: 10
dmi.chassis.vendor: HP
dmi.ec.firmware.release: 69.82
dmi.modalias:
dmi:bvnHP:bvrP78Ver.01.38:bd12/29/2020:br1.38:efr69.82:svnHP:pnHPEliteBook840G4:pvr:rvnHP:rn828C:rvrKBCVersion45.52:cvnHP:ct10:cvr:sku2FW43UC#ABA:pfa103C_5336ANHPEliteBook:
dmi.product.family: 103C_5336AN HP EliteBook
dmi.product.name: HP EliteBook 840 G4
dmi.product.sku: 2FW43UC#ABA
dmi.sys.vendor: HP
** Affects: linux-hwe-7.0 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug apport-hook-error noble wayland-session
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https://bugs.launchpad.net/bugs/2163479
Title:
I cannot reduce my display light not with the settings options or even
with fn + f5
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