Arch Linux

pun1sher729

Member

Registered: 2022-12-27

Posts: 1

Brightness stuck on max on Dell g15 5525

I'm unable to change the brightness, it is stuck on max.
Tried xbacklight, but doesn't work.
Running a AMD Ryzen 7 6800H with nvidia 3060

Any help?
Thanks

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 23,170

Re: Brightness stuck on max on Dell g15 5525

xbacklight only works with xf86-video-intel, install acpilight instead which uses native acpi handlers

173brian

Member

Registered: 2018-08-28

Posts: 11

Re: Brightness stuck on max on Dell g15 5525

I assume because you're trying to run xbacklight that you use X11 for your display. X11 includes the xrandr package as a dependency, and serves as the utility that I use for updating my backlight. By running just 'xrandr' you should get a list of different displays and connection information, including a device that's labelled as your connected display. Therefore running the command 'xrandr | grep " connected"' will give you details about your current display and utilizing the command 'xrandr | grep " connected" | cut -f1 -d" "' will further filter your output to just your screen identifier. Once you have your screen name you can use the xrandr command again to set your screen brightness. You'll want to use the --output option to specify your screen name, and the --brightness option to set your brightness level to a range between 0 and 1.
For example, my connected display name is "eDP", so when I set my brightness I write the command:
xrandr --output eDP --brightness .5 # 50% brightness
or
xrandr --output eDP --brightness 1 # 100% brightness
Technically speaking you can do values greater than 1.0 for your brightness settings, but .1-1 is the normal range.
Hope this helps!

Head_on_a_Stick

Member

From: The Wirral

Registered: 2014-02-20

Posts: 8,269

Website

Re: Brightness stuck on max on Dell g15 5525

xrandr can't control the screen backlight. Using the "--brightness" option with that only changes the gamma values, which hobbles your colour gamut. Use acpilight or brightnessctl instead.

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uleiars

Member

Registered: 2023-01-10

Posts: 1

Re: Brightness stuck on max on Dell g15 5525

If you have this as a kernel parameter remove it or comment it out and check if it works:

acpi_backlight=none

It worked for me. I had to add it at one point for this exact reason, brightness stuck on max.

radiomike

Member

Registered: 2013-12-19

Posts: 73

Re: Brightness stuck on max on Dell g15 5525

What are the contents of

/sys/class/backlight/

Also, how are you configuring optimus on your machine?

Are you are using PRIME, nvidia-xrun, or optimus-manager etc and making the nvidia card the main card for X? If so, then, because the internal display is physically attached to the internal gpu, the backlight may be assigned to the amd card, a backlight control is also produced for the nvidia card, but because no display is attached to it, it won't do anything. Unfortunately, if X is attached to the nvidia card, it/your DE will default to using the nvidia.
If this is the case, you can set the backlight by writing directly to

 /sys/class/backlight/amdgpu_bl0/brightness

the actual name may vary, but that's how it appears for me with a 4800H and 2060 based laptop. You should also be able to control the backlight when the amd card is set as your main card and, by default any changes you make should save and restore on reboot and should stay the same when using the nvidia card. As mentioned Acpilight and brightnessctl can both be used to set brightness on the amd card, but you'll need to make sure that you specify the amd card.

If you've disabled the amd gpu in bios, then it's possible the backlight may not be attached to any device and be uncontrollable as a result - this has certainly been the case with some kernel and nvidia driver versions, but I'm not sure if it's still an issue.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 23,170

Re: Brightness stuck on max on Dell g15 5525

Instead of various speculations I suggest to wait for the OP to actually return. As a matter of fact if the display is driven by anything that isn't the outdated xf86-video-intel then standard xbacklight is expected to and will simply not work, acpilight should on the other hand, assuming they do have a valid backlight device, which is technically something nvidia has enabled a while ago.

c_alzate

Member

Registered: 2023-01-13

Posts: 3

Re: Brightness stuck on max on Dell g15 5525

If you have this as a kernel parameter remove it or comment it out and check if it works:

acpi_backlight=none

It worked for me. I had to add it at one point for this exact reason, brightness stuck on max.

Yes, three days ago I had the same problem and I solved it in the same way. Check it out to try other options
https://wiki.archlinux.org/title/backli … ne_options