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I'm on a fresh installation of Ubuntu and planning to install i3wm. Unfortunately, the brightness is completely stuck on the maximum, rendering it basically torture to use during the night. Neither the brightness keys on my keyboard nor the brightness slider on the top right dropdown do anything. The brightness keys do show that the brightness is decreasing on the slider but it doesn't actually change at all. Please help! I'm using a Lenovo Flex 5 14.

Edit: It's definitely not the laptop itself's problem because the brightness buttons worked when I was on Windows and when I shut down the computer, the space around the Shut Down prompt is darker.

spokify
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2 Answers2

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Try changing it with xrandr

xrandr --output <display> --brightness <value between 0 and 1>

If you are unsure about the display name just press tab once you get to it.

For example I would use:

xrandr --output eDP-1-1 --brightness .5

You can try to use xbacklight

Or you could try the application brightness-controller . See the Github page or install with

sudo add-apt-repository ppa:apandada1/brightness-controller
sudo apt update
sudo apt install brightness-controller
totalynotanoob
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  • When using xrandr --output and then tabbing it gives me Failed to get size of gamma for output default – spokify Aug 31 '20 at 15:30
  • try xrandr -q | grep " connected" . You shoud get a list with the first entry beeing display name. – totalynotanoob Aug 31 '20 at 15:41
  • Here's the output: xrandr: Failed to get size of gamma for output default default connected primary 1920x1080+0+0 0mm x 0mm – spokify Aug 31 '20 at 16:00
  • hm. have you tried to not give any display and just xrandr --output --brightness <value between 0 and 1>. – totalynotanoob Aug 31 '20 at 16:15
  • Doesn't work. xrandr: unrecognized option '0.4' – spokify Aug 31 '20 at 16:23
  • the same happens for me without a display chosen. so you could either try something like primary or default. Other than that you might want to try to use xbacklight or brightness-controller. – totalynotanoob Aug 31 '20 at 16:27
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Fixed it! Turns out this is an issue with my laptop's APU, the 4500u. I had to update the kernel to 5.8 and then boot without Secure Boot in the BIOS.

spokify
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