There is a solution to this, albeit not the greatest. However, it does point to how the devs can fix this.
Apparently, for reasons known only to itself, Canonical removes some of the drivers from the kernels when releasing them. A maintainer, Zabbly, maintains the mainline kernel but including the removed bits. https://github.com/zabbly/linux This also solves another problem, probably related, to do with the screen periodically blanking. https://ubuntuforums.org/showthread.php?t=2499896 I shall create a new bug for the latter problem, and link it to this one. -- 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: Confirmed 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! ——————— UPDATES ——————— • See comment #7 — This is somehow linked to the Night Light. • Even when Night Light is permanently turned off, the screen still (sometimes; it's intermittent) goes bright when… — Playing a video full screen (e.g. VLC, YouTube). — Chrome gives a pop-up dialogue (e.g. downloading) or a notification (e.g. Calendar notification). ————————— TESTED ON ————————— • Ubuntu 22.04 — Kernel 6.2.0-39 and prior works correctly — Kernels 6.5.0-14 & 6.5.0.15 have 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) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-signed-hwe-6.5/+bug/2049248/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
