Brightness doesn't change

Hello. I got a new laptop, where I can't change the brightness of the screen and it's hurting my eyes if I look at it for a long time.

I tried to change settings in Power Management Preferences and also with Applet of brightness, but any setting I try, no matter if it's 0 or 100% the brightness stay the same. It also doesn't change if I'm on battery or AC power. Also the 2 Fn keys on keyboard show changing brightness but there doesn't seem to be any change on screen.

Here are my info:

  Host: Legion-Y540-15IRH-PG0 Kernel: 5.4.0-42-generic x86_64 bits: 64 
  Desktop: MATE 1.24.0 Distro: Ubuntu 20.04.1 LTS (Focal Fossa) 
  Type: Laptop System: LENOVO product: 81SY v: Legion Y540-15IRH-PG0 
  serial: <superuser/root required> 
  Mobo: LENOVO model: LNVNB161216 v: NO DPK 
  serial: <superuser/root required> UEFI: LENOVO v: BHCN36WW 
  date: 02/10/2020 
  Topology: Quad Core model: Intel Core i5-9300HF bits: 64 type: MT MCP 
  L2 cache: 8192 KiB 
  Speed: 900 MHz min/max: 800/4100 MHz Core speeds (MHz): 1: 900 2: 900 
  3: 900 4: 900 5: 900 6: 900 7: 900 8: 900 
  Device-1: NVIDIA TU117M [GeForce GTX 1650 Mobile / Max-Q] driver: nvidia 
  v: 435.21 
  Display: x11 server: X.Org 1.20.8 driver: nvidia 
  unloaded: fbdev,modesetting,nouveau,vesa resolution: 1920x1080~60Hz 
  OpenGL: renderer: N/A v: N/A 
  Device-1: Intel Cannon Lake PCH cAVS driver: snd_hda_intel 
  Device-2: NVIDIA driver: snd_hda_intel 
  Sound Server: ALSA v: k5.4.0-42-generic 
  Device-1: Intel Wireless-AC 9560 [Jefferson Peak] driver: iwlwifi 
  Device-2: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet 
  driver: r8169 
  Local Storage: total: 1.14 TiB used: 15.26 GiB (1.3%) 
  ID-1: /dev/nvme0n1 vendor: Micron model: MTFDHBA256TCK size: 238.47 GiB 
  ID-2: /dev/sda vendor: Seagate model: ST1000LM049-2GH172 size: 931.51 GiB 

Hope that info help, let me know if you need something else, and remember I'm not very familiar in terminal and those stuff, I mostly always prefer graphical things.

So if anyone have some ideas what could be wrong please let me know...

Hello there. Here are an alternative that you can try. Open up a terminal and paste the below command:
xrandr | grep " connected" | cut -f1 -d " "

Then, run the command below (replace the X with whatever result you get from above command:
xrandr --output X --brightness 0.6

Let me know how it goes.

Hello @juanquintero. Welcome to community.

I got DP-4 from first command, pasting that and running second command dim the screen a bit, but after few seconds or if I move mouse it goes back to full brightness.

Anyone have any idea what I should do next? Or how to fix this?

Hi :slight_smile:
Im advising you to upgrade to a new kernel.
I just bought a new thinkpad 11e and got no brightness control up to the moment i upgraded the kernel.
You can do it with mainline :

sudo apt-add-repository -y ppa:cappelikan/ppa
sudo apt update
sudo apt install mainline

next install a higher one like 5.8.3.
Reboot and go to BIOS, disable secure boot (the signature have changed with new kernel, its not gonna boot with secure boot)

Once booted check if you booted new kernel with uname -a :

└──╼ $uname -a
Linux apbook08u 5.8.3-050803-generic #202008211236 SMP Fri Aug 21 12:38:46 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Should be better ! :slight_smile:

For anyone looking for a software solution (not on a laptop here)
There is a package called "brightness-controller" although I can't remember where I got it from, I think it was this one:

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