Comment 0 for bug 2049248

Since kernel 6.5, monitor brightness is set to 100%, and cannot be changed: The brightness controls have disappeared from Settings, and brightness doesn't respond to the keypad controls.

See the attached screenshot, showing the difference between the settings in kernels 6.2 and 6.5.

This applies to Ubuntu 22.04 and 23.10, whether using Wayland or X.Org.

It's possible (when using X.Org) to adjust the brightness with…

$ xrandr --output [monitor] --brightness [brightness]

e.g. on my machine…

$ xrandr --output eDP-1 --brightness 0.5

… but, unfortunately, it doesn't last long — anywhere between a less than a second later and about a minute later, the screen reverts to 100% brightness.

As a workaround, I am running the following command in the background…

$ while true; do xrandr --output eDP-1 --brightness 0.5; sleep 1s; done

… which results in the screen at the correct brightness, but frequently flashing!

Tested on:

• Ubuntu 22.04
— Kernel 6.2.0-39 and prior works correctly
— Kernel 6.5.0-14 has the problem

• Ubuntu 23.10
— Kernel 6.5.0-9 has the problem

$ sudo lshw -numeric -C display
  *-display
       description: VGA compatible controller
       product: CometLake-S GT2 [UHD Graphics 630] [8086:9BC5]
       vendor: Intel Corporation [8086]
       physical id: 2
       bus info: pci@0000:00:02.0
       logical name: /dev/fb0
       version: 05
       width: 64 bits
       clock: 33MHz
       capabilities: pciexpress msi pm vga_controller bus_master cap_list rom fb
       configuration: depth=32 driver=i915 latency=0 resolution=1920,1080
       resources: irq:145 memory:c1000000-c1ffffff memory:d0000000-dfffffff ioport:3000(size=64) memory:c0000-dffff

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: linux-image-6.5.0-14-generic 6.5.0-14.14~22.04.1
ProcVersionSignature: Ubuntu 6.5.0-14.14~22.04.1-generic 6.5.3
Uname: Linux 6.5.0-14-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sat Jan 13 07:19:58 2024
InstallationDate: Installed on 2022-08-28 (502 days ago)
InstallationMedia: Ubuntu 22.04.1 LTS "Jammy Jellyfish" - Release amd64 (20220809.1)
SourcePackage: linux-signed-hwe-6.5
UpgradeStatus: No upgrade log present (probably fresh install)