Screen brightness unable to be changed in 20.04, usual solutions don't work

Screen brightness unable to be changed in 20.04, usual solutions don't work

I’ve got asus with nvidia graphics. Screen brightness is at maximum and wont budge. Installing brightness-controller, which worked for 16.04 on the same hardware, doesn’t work now. I’ve also tried, to no avail, the following:

  • f.lux
  • redshift
  • Editing /etc/default/grub with multiple suggested configurations (with sudo update-grub and reboot after each modification).
  • Editing /usr/share/X11/xorg.conf.d/80-backlight.conf and /usr/share/X11/xorg.conf.d/20-intel.conf (with reboots afterwards)
  • Editing directly /sys/class/backlight/acpi_video0/brightness and /sys/class/backlight/acpi_video1/brightness (they take values from 1 to 10)

Some outputs:


$ xrandr
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080
default connected primary 1920x1080+0+0 0mm x 0mm
  1920x1080    77.00*

$ xrandr --output default --brightness 0.8
xrandr: Gamma size is 0.


$ ls /sys/class/backlight/
acpi_video0  acpi_video1


$ cat /usr/share/X11/xorg.conf.d/20-intel.conf
Section "Device"
        Identifier  "card0"
        Driver      "nvidia"
        Option      "Backlight"  "acpi_video1"
        BusID      "PCI:0:2:0"


$ cat /usr/share/X11/xorg.conf.d/80-backlight.conf
Section "Device"
    Identifier  "Intel Graphics"
    Driver      "intel"
    Option      "AccelMethod"    "sna"
    Option      "Backlight"      "acpi_video0"
    BusID      "PCI:0:2:0"


$ cat /etc/default/grub
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#  info -f grub -n 'Simple configuration'

GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_osi="
##GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=video1"

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)

# Uncomment to disable graphical terminal (grub-pc only)

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux

# Uncomment to disable generation of recovery mode menu entries

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"


$ cat /usr/share/X11/xorg.conf.d/10-nvidia-brightness.conf
Section "Device"
    Identifier    "Device0"
    Driver        "nvidia"
    VendorName    "NVIDIA Corporation"
    BoardName      "Quadro K1000M"
    Option        "RegistryDwords" "EnableBrightnessControl=1"

Usage of the laptop keys changes /sys/class/backlight/acpi_video0/brightness, but without apparent further effect.


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