I will repeat the above from an earlier post. I suggest you search and read a little instead of depending upon the rest of us to hand you the answer. I know that several of those had solutions posted. I would have to do the same to make a good suggestion.
Please remember that all of us are volunteering our time, we likely do not have the exact same equipment and software you do, and we can provide advice but not a bulletproof answer.
can u please guide me in the right direction, it isn’t a GPU issue as I’ve ruled it out I’ve tried different kernels and that didn’t either help. I’ve also tried a bunch of grub config things. where do I look next?
ISTR that there may be a brightness setting somewhere under /proc or /sys for the laptop screen. I don’t remember where and cannot at the moment look. There may be one only for the iGPU or dGPU or both iGPU & dGPU depending upon the hardware and the OS. Since I would have to research that it seems better to ask you to do that research.
I also seem to recall that there may be a max brightness value as well as a brightness value.
UPDATE:
The settings may exist under /sys/class/backlight/
# ls -l /sys/class/backlight/intel_backlight/
total 0
-r--r--r--. 1 root root 4096 Oct 31 10:11 actual_brightness
-rw-r--r--. 1 root root 4096 Oct 31 10:11 bl_power
-rw-r--r--. 1 root root 4096 Oct 31 09:16 brightness
lrwxrwxrwx. 1 root root 0 Oct 31 10:11 device -> ../../card0-eDP-1
-r--r--r--. 1 root root 4096 Oct 31 09:16 max_brightness
drwxr-xr-x. 2 root root 0 Oct 31 09:16 power
-r--r--r--. 1 root root 4096 Oct 31 10:11 scale
lrwxrwxrwx. 1 root root 0 Oct 31 09:16 subsystem -> ../../../../../../../class/backlight
-r--r--r--. 1 root root 4096 Oct 31 09:16 type
-rw-r--r--. 1 root root 4096 Oct 31 09:16 uevent
# cat /sys/class/backlight/intel_backlight/brightness
7368
# cat /sys/class/backlight/intel_backlight/max_brightness
24000
# chmod u+w /sys/class/backlight/intel_backlight/brightness
# ls -l /sys/class/backlight/intel_backlight/brightness
-rw-r--r--. 1 root root 4096 Nov 1 12:45 /sys/class/backlight/intel_backlight/brightness
# echo "8000" > /sys/class/backlight/intel_backlight/brightness
# cat /sys/class/backlight/intel_backlight/brightness
8000
Thus I see that brightness is not writable, but it can be changed using the chmod command, then modified.
I also see that the max allowed value is about 3 times the current value so I reset it slightly higher so I could see the effect.
switched the permission but getting an input/output error when I try to write to the files. I am sorry about the time this is taking, but I really appreciate ur efforts.
and the man page referenced in the Docs line there led me to find
# ls /var/lib/systemd/backlight
pci-0000:00:02.0:backlight:intel_backlight pci-0000:00:14.0-usb-0:8:1.2:leds:asus::kbd_backlight
# cat /var/lib/systemd/backlight/pci-0000:00:02.0:backlight:intel_backlight
12595
which is the value that should be saved during shutdown and restored during startup/login. The /sys filesystem is after all a tmpfs and disappears when shutdown so systemd saves the value to disk.
That command line is long because the system needs it to be so. It also shows on my screen as 4 separate lines. Please do not alter anything you copy and paste so we can see it exactly as you see it.
I think it probably showed like this when you copied it.
The fact that this rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 appears twice shows you installed the nvidia drivers twice. The second copy of that may be deleted.
Why is this amdgpu.backlight=0 appearing there? You are having problems with the backlight brightness and it is possible this affects that.
I have deleted both the duplicate and the amdgpu.backlight=0, which both must have resulted from 1 of the 40 solutions I’ve tried. This issue has ranged across all distros and I can see that it’s not faulty hardware because for a few seconds before the distro loads up I get full brightness. Additionally the slider does work and alters a value between 0 and 255 in /sys/class/backlight/admgpu_bl0/brightness, oddly it does this backwards when the slider is empty its at 255 and the screen is at the max of it’s very limited brightness while when it’s full it is at 0 and at minimal brightness. As I previously stated I’ve checked close to 40 similar issues many with solutions and had 0 success, I haven’t even been able to change the aforementioned files manually due to a write error: input/output error that occurred after U tried to write when I changed permissions. I know I’ve already taken a lot of your time but sir please where do I go next?
just used xbacklight and it outputted the following: No outputs have backlight property. Could it be the system doesn’t read my backlight and I’m seeing without a backlight?
update: when running the systemctl enable backlight command it outputted, Failed to enable unit: Unit file backlight.service does not exist.
If you noted the command I posted you saw systemctl status systemd-backlight@backlight.service The same name would be used to enable or disable that service.
However, if you are in as root (not just using sudo) you should be able to do the chmod and make a change to the content of the brightness file as I showed above and repeat here.
The # at the beginning of those command lines shows I was in the root environment, which can be achieved by using sudo su -
Note that the path I used may or may not match for you since the ‘intel_backlight’ directory is hardware dependent. Using ls /sys/class/backlight should give you the proper directory on your system.
I have 3 files regarding brightness in my /sys/class/backlight/amdgpu_0 folder:
1.brightness: which the slider changes to a value from 0 to 255, and I can write to it,
this does nothing except change screen a bit brighter when at 0 and dimmer at 255.
2.max_brightness: which is set at 255 and cannot be written to regardless of permission.
(when try to write it outputs an input/output error).
3.actual_brightness: is at 0 and like max_brightness it cannot be written to (same input/output error).
To sum it up writing to that file doesn’t help me as it is functioning fine with the slider and the number reflects that, rather the screen has some other intrinsic issue
Additionally, I tried to set up ddcutil to use a gnome extension brightness changer and when I used ddcutil capabilities | grep "Feature: 10" it outputted Display not found. Please lmk if this along with all of the other info I’ve given points to the issue. This problem has been eating away at my days.
thx for the suggestion, the program works and changes the brightness value, but my issue lies beneath that. It seems the slider and brightness file work but my backlight is stuck dim with only slight variation in brightness and dimness
I spent half an hour tying to fix the brightness, until I’ve seen this.
I restarted my toshiba satellite L750 labtop with an older kernel and my brightness options worked again.