Public bug reported:
Summary
Brightness control works correctly with kernel 6.17.0-35-generic but is
broken with 7.0.0-28-generic on a Dell Latitude 5530 with Intel Iris Xe
graphics.
System Information
Ubuntu: 24.04.4 LTS
Laptop: Dell Latitude 5530
GPU: Intel Corporation Alder Lake-UP3 GT2 [Iris Xe Graphics]
Working kernel: 6.17.0-35-generic
Broken kernel: 7.0.0-28-generic (package version 7.0.0-28.28~24.04.1)
Expected Result
The internal display brightness should be adjustable using:
GNOME brightness slider
Keyboard brightness (Fn) keys
brightnessctl
This is the behavior observed when running kernel 6.17.0-35-generic.
Actual Result
With kernel 7.0.0-28-generic, the display briefly appears bright during
early boot and then becomes dim. After the kernel initializes, the
brightness remains fixed.
The following all update the reported brightness value correctly:
GNOME brightness slider
Keyboard brightness (Fn) keys
brightnessctl
Both:
/sys/class/backlight/intel_backlight/brightness
/sys/class/backlight/intel_backlight/actual_brightness
change as expected, but the physical panel brightness never changes.
The issue occurs under both Wayland and Xorg.
Regression
This issue is fully reproducible.
Booting 6.17.0-35-generic restores normal brightness control.
Booting 7.0.0-28-generic reproduces the problem every time.
No other configuration changes are required; only the kernel version
differs.
Additional Information
I first noticed the issue after a system freeze while an external HDMI
monitor was connected. However, I cannot confirm whether the freeze
caused the issue or whether it was already present.
The regression is reproducible solely by switching between kernel
versions.
During troubleshooting I confirmed that:
intel_backlight is present.
brightnessctl successfully updates both brightness and actual_brightness.
The brightness slider and keyboard brightness keys behave normally from
userspace but do not affect the panel on kernel 7.0.0-28.
The issue does not depend on the display server, as it occurs under both
Wayland and Xorg.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-35-generic 6.17.0-35.35~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-35.35~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-35-generic x86_64
ApportVersion: 2.28.2-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: moiz 2624 F.... wireplumber
/dev/snd/seq: moiz 2621 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Thu Aug 6 19:24:47 2026
InstallationDate: Installed on 2026-04-24 (104 days ago)
InstallationMedia: Ubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
MachineType: Dell Inc. Latitude 5530
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=/boot/vmlinuz-6.17.0-35-generic
root=UUID=f45f21fb-3ead-41ca-b17a-6af37060d752 ro quiet splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-6.17.0-35-generic N/A
linux-backports-modules-6.17.0-35-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/26/2025
dmi.bios.release: 1.33
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.33.0
dmi.board.name: 0V9MN4
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.ec.firmware.release: 1.17
dmi.modalias:
dmi:bvnDellInc.:bvr1.33.0:bd11/26/2025:br1.33:efr1.17:svnDellInc.:pnLatitude5530:pvr:rvnDellInc.:rn0V9MN4:rvrA00:cvnDellInc.:ct10:cvr:sku0B06:
dmi.product.family: Latitude
dmi.product.name: Latitude 5530
dmi.product.sku: 0B06
dmi.sys.vendor: Dell Inc.
** Affects: linux-hwe-6.17 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
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https://bugs.launchpad.net/bugs/2162965
Title:
Brightness control regression on Dell Latitude 5530 with Intel Iris Xe
between 6.17.0-35 and 7.0.0-28
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