Public bug reported:
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)
** Affects: linux-signed-hwe-6.5 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug jammy
** Attachment added: "Screenshot of the settings with kernels 6.2 and 6.5"
https://bugs.launchpad.net/bugs/2049248/+attachment/5738907/+files/Brightness%20problem.png
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You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux-signed-hwe-6.5 in Ubuntu.
https://bugs.launchpad.net/bugs/2049248
Title:
Kernel 6.5 breaks display brightness controls and sets it to 100% all
the time
Status in linux-signed-hwe-6.5 package in Ubuntu:
New
Bug description:
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)
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https://bugs.launchpad.net/ubuntu/+source/linux-signed-hwe-6.5/+bug/2049248/+subscriptions
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