My Fn+F8 and Fn+F9 keys to change the screen's brightness appear to no longer work on my Thinkpad laptop.
# ls /sys/class/backlight/ thinkpad_screen
Some guide told me to make this:
# cat /usr/share/X11/xorg.conf.d/20-intel.conf Section "Device" Identifier "card0" Driver "intel" Option "Backlight" "intel_backlight" BusID "PCI:0:2:0" EndSection
And someone else said to do this:
# cat /usr/share/X11/xorg.conf.d/20-nvidia.conf Section "Device" Identifier "NVIDIA" Driver "nvidia" Option "NoLogo" "True" Option "RegistryDwords" "EnableBrightnessControl=1" EndSection
This is my GRUB CMDLINE_LINUX_DEFAULT line, in case it's relevant:
GRUB_CMDLINE_LINUX_DEFAULT="nosplash nomodeset acpi_osi=Linux acpi_backlight=vendor"
The Ubuntu wiki page on backlight issues says
Add just kernel parameters thinkpad-acpi.brightness_enable=1 acpi_backlight=vendor to /boot/grub/menu.lst . Execute: sudo update grub
but I don't have a menu.lst and I suspect this is outdated.
Doing something like this does not work:
echo 10 > /sys/class/backlight/thinkpad_screen/brightness