I just got a new Lenovo with an Intel Core i3-1115G5 with integrated graphics. After a fresh install of Ubuntu 20.04 the Fn keys that are supposed to control the brightness do not work. The brightness slider in the system menu as well as the one in Settings->Power are missing. I tried installing xbacklight, but the command xbacklight -get doesn't yield any output and the -set [number] option does not produce any change in brightness.
Here's the output of lspci:
$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Device 9a78 (rev 01)
I tried modifying the /etc/default/grub file so that
GRB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"
updated the grub and restarted but it didn't have any effect.
I also tried this solution but it didn't work. The command ls /sys/class/backlight/ gives no output. I also tried the find command as in the accepted answer here but it didn't yield anything related to intel:
$sudo find /sys/ -type f -iname '*brightness*'
/sys/devices/platform/i8042/serio0/input/input2/input2::numlock/brightness
/sys/devices/platform/i8042/serio0/input/input2/input2::numlock/max_brightness
/sys/devices/platform/i8042/serio0/input/input2/input2::capslock/brightness
/sys/devices/platform/i8042/serio0/input/input2/input2::capslock/max_brightness
/sys/devices/platform/i8042/serio0/input/input2/input2::scrolllock/brightness
/sys/devices/platform/i8042/serio0/input/input2/input2::scrolllock/max_brightness
/sys/devices/pci0000:00/0000:00:14.3/leds/phy0-led/brightness
/sys/devices/pci0000:00/0000:00:14.3/leds/phy0-led/max_brightness
/sys/module/video/parameters/hw_changes_brightness
/sys/module/video/parameters/brightness_switch_enabled
/sys/module/i915/parameters/invert_brightness
I nevertheless tried creating a file /usr/share/X11/xorg.conf.d/20-intel.conf with contents:
Section "Device"
Identifier "card0"
Driver "intel"
Option "Backlight" "intel_backlight"
BusID "PCI:0:2:0"
EndSection
but it just produced a black screen after logging out. I got the log-in screen again after pressing the power button. After logging in the problem was not resolved.
I don't know what else to try... Any help is highly appreciated!
