SOLVED Impossible to change the brightness

UPDATE: 27082022

Source: Ask Ubuntu

This made the job with Vorago Stela100 in Debian 11:

sudo vi /usr/share/X11/xorg.conf.d/20-intel.conf:

# begin file contents

Section "Device"

Identifier "card0"

Driver "intel"

Option "Backlight" "intel_backlight"

BusID "PCI:0:2:0"

EndSection

# end file contents

sudo vi /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="acpi_osi= pci=noaer"

sudo update-grub

o0o

Yes yes yes! I'm happy: this works for me (using Debian):

sudo vim /etc/default/grub 

GRUB_CMDLINE_LINUX_DEFAULT="quiet acpi_osi=Linux acpi_backlight=video" 
GRUB_CMDLINE_LINUX="" 

sudo update-grub 
sudo reboot

ACPI error messages still persists when the system startup (AE_NOT_FOUND), but Fn+F11 and Fn+F12 keys are driving the brightness correctly.

When I type in the command line this:

~$ for i in /sys/class/backlight/*; do echo -e "\n $i"; cat $i/{brightness,max_brightness,actual_brightness}; done

Displays this:

/sys/class/backlight/acpi_video0
85
100
85

/sys/class/backlight/intel_backlight
4882
4882
4882