Nico's blog

FreeBSD Backlight/screen brightness on my Thinkpad X1

Context

As usual, writing this mostly for me to remember, but maybe useful to others.

I wanted to control backlight on my Thinkpad X1 Carbon running FreeBSD, but using Fn + F5 or F6 would do nothing.

I found the solution on the FreeBSD forums and the FreeBSD-ACPI Mailing list:

Let's fix it

Add this line to /boot/loader.conf/:

# ACPI IBM for Backlight etc
acpi_ibm_load="YES"

and then create /etc/devd/acpi_ibm_brightness.conf:

notify 20 {
       match "system" "ACPI";
       match "subsystem" "IBM";
       match "notify" "0x10";
       action "/usr/bin/backlight incr 10";
 };

notify 20 {
       match "system" "ACPI";
       match "subsystem" "IBM";
       match "notify" "0x11";
       action "/usr/bin/backlight decr 10";
 };

And voilà !

You can either reboot, or just run kldload acpi_ibm to load the kernel module, and you'll be able to control the screen backlight with Fn + F5/F6.

Tags: FreeBSD