I recently blew new life into an old iMac (21,5" late-2012) for my daughter, using F37 gnome-desktop.
The live USB seemed to have no problem controlling the display brightness. Even the automatic light-sensor worked.
I noticed after the install was done, the installation itself doesn’t have any ability to control the screen brightness anymore.
On the live USB I had an extra slider in the gnome top corner menu, for the brightness. Now it’s gone. What other packages do I need to install to bring that back?
I’m working through figuring out the same thing on my system - the resources I’m working with are this reference on how Linux determines what driver handles the backlight:
Okay, I tried this, but unfortunately I have no success with this.
I did learn how I can disable the the fancy Fedora bootscreen so I can follow the systemd initialization during boot. (which I’m leaving off for now so I can see wth is going on)
I also learned that; if I try to look for backlight devices with ls /sys/class/backlight i see no devices at all.
I just switched from the nvidia driver to the nouveau driver, i don’t know if that is the reason it’s not detected (backlight didn’t work in both cases, so that’s why i tried switching drivers). But if it does work with the nvidia driver … I can say bye-bye to Wayland… That would be a bummer. I’ll try to keep updating this thread with any findings.
Tried ls /sys/class/backlight again, with the nvidia proprietary drivers. Still no devices to be found there. Do specific driver packages exist for specific Apple computers to deal with these specific device features?
I thought I was going mental, but no… the install USB does have the slider. It knows what hardware to address. What’s the best way to backpedal this information, so I can implement it on the actual installation… I’ve actually had this experience before, where the live install actually gave me a better experience then the install itself… How is this possible?
It even uses the light sensor.
ls /sys/class/backlight now also results acpi_video0
idk if this is in any way related, but i had this somewhat similar issue after the kernel update from 6.0 to 6.1 on a late 2011 mbp - it stuck on 100% brightness with brightness key not responding and no slider available (though i’m running kde).
and since i kind of accepted that kernel updates keep breaking things past version 6 at least on my system i decided against posting it here. so i just went for a previous kernlev version and stuck with it indefinitely.
Okay, I e-mailed Hans and he replied me with a temporary fix and noted that they are aware of this issue. It would probably be fixed in the coming stable kernel series. Here’s the reply I got:
Thank you for reporting this and sorry about the regression.
This issue was already reported to me recently
and a set of fixes is on its way to the stable
kernel series:
% doas ddcutil capabilities | grep "Feature: 10"
Feature: 10 (Brightness)
% doas ddcutil getvcp 10
VCP code 0x10 (Brightness ): current value = 9408, max value = 65535
% doas ddcutil setvcp 10 20000
same problem here :
no brightness control from gnome settings nor from apple keyboard.
apple imac 27 14,2
Fedora 38 (6.2.6-300.fc38.x86_64)
akmod-nvidia driver from rpm-fusion repo.
(I tried the nouveau driver, but it was unsuable because of glitches on an external apple display)