Thinkpad T470 Issue changing backlight

bt108

System:
GhostBSD 25.02-R14.3p4
64bit
Thinkpad T470
Fresh install.

Issue:
When I run;
sysctl hw.acpi.video.lcd0.brightness=VALUE
There is no change in backlight, setting 0 or 100 both look the same.

What I tried;
I tried loading (kldload) acpi_video and acpi_ibm, but no change.

systemctl -a | grep backlight and systemctl -a | grep brightness returns these lines;
hw.i915kms.enable_dpcd_backlight: -1 compat.linuxkpi.i915_enable_dpcd_backlight: -1 hw.i915kms.invert_brightness: 0 hw.acpi.video.lcd0.brightness: 10 compat.linuxkpi.i915_invert_brightness: 0

nevillehay

Have you tried the backlight command?
Also being a ThinkPad you may be able to get the hotkeys working by loading the acpi_ibm module

Put acpi_ibm_load="YES" into your

/boot/loader.conf file, reboot and see if you can adjust brightness with the hotkeys

bt108

nevillehay
Thank you for your reply!
The backlight command works after I added myself to the video group.
The hotkeys don't work after doing what you said.
I tried making my own keybindings, a normal keybinding works but binding the "Monitor brightness up|down" buttons does not give a result. Maybe the are captured / handled by an other program before MATE gets it?

Any suggestion / best practice to get the hotkeys working?

In any case I am very happy I can change the backlight now! Thank you

nevillehay

You can try adding this line to /boot/loader.conf

acpi_video_load="YES"

Reboot and see if that fixes the hotkeys

nevillehay

Also have a look here

https://cyber.dabamos.de/unix/x230/

You may need to add some entries to devd.conf

To get the hotkeys working