Public bug reported:
Summary:
After installing Ubuntu, the display brightness is significantly lower
than in Windows, even when the brightness is set to 100%. The screen
remains noticeably dim, although Ubuntu reports that the backlight is
already at its maximum value.
Hardware:
Laptop: Dell Latitude 7490
Graphics: Intel UHD Graphics 620 (Kaby Lake-R GT2)
Graphics Driver: i915
Boot Mode: UEFI
Installation: Dual boot with Windows
Software:
Ubuntu Version: Ubuntu 26.04 LTS (Resolute)
Kernel: 7.0.0-28-generic
Problem:
The screen is much dimmer in Ubuntu than in Windows.
The brightness slider works, but even at 100% the display brightness is
significantly lower than Windows on the same hardware.
The hardware backlight appears to be operating at maximum, but the
display is still dim.
Diagnostic Information:
Current brightness:
cat /sys/class/backlight/intel_backlight/brightness
1023
Actual brightness:
cat /sys/class/backlight/intel_backlight/actual_brightness
1023
Maximum brightness:
cat /sys/class/backlight/intel_backlight/max_brightness
1023
Graphics device:
lspci | grep -i -E "vga|3d|display"
00:02.0 VGA compatible controller:
Intel Corporation Kaby Lake-R GT2 [UHD Graphics 620]
Driver:
sudo lshw -C display
driver=i915
Backlight device:
ls /sys/class/backlight/
intel_backlight
Troubleshooting Performed
Verified brightness slider is set to 100%.
Night Light is disabled.
Verified /sys/class/backlight/intel_backlight/brightness and actual_brightness
are both at maximum (1023).
Tried changing brightness using:
xrandr --output eDP-1 --brightness 1
xrandr --output eDP-1 --brightness 1.5
No visible change.
Added the kernel parameter:
i915.enable_psr=0
Updated GRUB and rebooted.
No improvement.
ubuntu-drivers list returned no additional drivers.
dmesg did not report any backlight-related errors.
Expected Behavior:
Ubuntu should achieve approximately the same maximum screen brightness as
Windows on the same hardware.
Actual Behavior:
Ubuntu reports maximum brightness, but the display remains significantly
dimmer than Windows.
Additional Information:
This issue is consistently reproducible after every reboot.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-28-generic 7.0.0-28.28
ProcVersionSignature: Ubuntu 7.0.0-28.28-generic 7.0.12
Uname: Linux 7.0.0-28-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: harsha 3393 F.... wireplumber
/dev/snd/seq: harsha 3377 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Mon Aug 3 16:13:11 2026
InstallationDate: Installed on 2026-07-28 (6 days ago)
InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
Lsusb:
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 1bcf:2b96 Sunplus Innovation Technology Inc.
Integrated_Webcam_HD
Bus 001 Device 003: ID 8087:0a2b Intel Corp. Bluetooth wireless interface
Bus 001 Device 004: ID 0a5c:5832 Broadcom Corp. BCM5880 Secure Applications
Processor Smartcard reader
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
MachineType: Dell Inc. Latitude 7490
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-7.0.0-28-generic
root=UUID=ff40b086-11cb-42c6-99a5-0008023755d3 ro quiet splash
i915.enable_psr=0 apci_backlight=native
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/08/2025
dmi.bios.release: 1.44
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.44.0
dmi.board.name: 0NFCCJ
dmi.board.vendor: Dell Inc.
dmi.board.version: A07
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvr1.44.0:bd04/08/2025:br1.44:svnDellInc.:pnLatitude7490:pvr:rvnDellInc.:rn0NFCCJ:rvrA07:cvnDellInc.:ct10:cvr:sku081C:pfaLatitude:
dmi.product.family: Latitude
dmi.product.name: Latitude 7490
dmi.product.sku: 081C
dmi.sys.vendor: Dell Inc.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2162725
Title:
Screen brightness significantly lower than Windows on Dell Latitude
7490 (Intel UHD Graphics 620)
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