Since last night (yes, I ran UpdateInTerminal) I’m no longer able to adjust my screen backlight/brightness via the F1 and F2 keys.
I am on a MacBookPro11,2, Gnome 43.2 and kernel 6.1.6-arch1-3.
So far I’ve tried to install the Gnome extension that uses ddcutil, which did not recognize any monitors. I added the “acpi_backlight=native” to my grub with no results. Also, I installed light but it outputs “No backlight controller was found, so we could not decide an automatic target. The current command will have no effect.” when run.
My best guess is that the backlight controller was not installed by the update, as /sys/class/backlight/ is empty. Nonetheless I do not know how to restore it or prompt its installation.
Since it was working before the update, it sounds like a kernel bug.
Was any kernel updated?
Did you try another kernel?
Have you… rebooted after the update? (I suppose you did, but I had to ask )
What is in the pacman log from the update Jan 16 when you updated it and then the backlight isn’t working. Check date and times around when this happened in … What are the updates?
I think it is a kernel bug too, but I’m merely a user, the kernel is a black box to me. I don’t think it has to do with the key bindings because the keyboard backlight adjustment and volume keys work fine.
Regarding trying another kernel, I’ve been looking for precise instructions to rollback but have not found them. I did try installing the lts kernel and headers but was unable to boot when selecting it from the boot options.
I’ve seen a couple other reports of brightness issues on bbs.archlinux.org and maybe the arch subreddit. Maybe try the LTS kernel to see if it works - and if so, some sort of kernel regression.
This is a serious issue, and suggests that something is probably wrong with your system. Unless you are doing something wrong in the process.
I would first troubleshoot that, since brightness control is minor in comparison.
Research the installation of LTS. It may have not been installed properly.
Weren’t there any error messages during installation?
Check your pacman.log for messages.
Before trying the LTS kernel, I’m reading a thread on the archlinux forum and they say that the problem was solved by removing the acpi_backlight=video from the kernel paramenters. I’m seeing in my /boot/grub/grub.cfg that I indeed have that as a kernel parameter but I don’t remember where it’s that parameter set, since the file /boot/grub/grub.cfg is re-created by grub-mkconfig every time grub or the kernel are updated if I remember correctly.
More reading… I set the acpi_backlight kernel parameter in /etc/default/grub. I’ll remove it, re-create /boot/grub/grub.cfg using grub-mkconfig, reboot, and let you know if that works.
Ironically my problem started without any acpi_backlight paramaters. I added it myself and cycled through the three possible definitions (native, video and vendor) and later removed it. Issue persists, in my case.
Perhaps I should also add that I cannot adjust the brightness at all as the slider is missing from my display settings. I can toggle “night light”, but that’s about it.
)