home » work in progress » laptop brightness buttons

Laptop Brightness Buttons

Laptop Brightness Buttons

19/02/2010: Toshiba A300 Brightness Buttons

19/02/2010: Toshiba A300 Brightness Buttons

Not unusually for a Linux laptop, my brightness buttons didn't work. I don't really find this an enormous problem, but having had this laptop for a while I decided to have a go at getting it working. Firstly, I found the location of the proc file for controlling brightness:

$ cat /proc/acpi/video/OVGA/DD03/brightness
levels:  10 25 35 50 60 75 90 100
current: 100

I then played with altering the brightness with:

$ sudo su
# echo -n 50 > /proc/acpi/video/OVGA/DD03/brightness

I then proceeded to write a script for controlling brightness with "brightness up" or "brightness down", which worked beautifully, once I enabled the user to be able to write to the above proc file.

Next step to determine the keystroke generated by the fn+f6/f7 keys by using "xev".

$ xev

I was surprised to see that they were already mapped to XF86MonBrightnessDown and XF86MonBrightnessUp, tested the keys again and sure enough they were working. But hang on, I haven't mapped anything to my script yet! Obviously there was nothing fundamentally wrong, except for the permissions on the file.

But after a reboot, they aren't working again, sure enough the permissions have been reset.

top

Laptop Brightness Buttons

Table of Contents

19/02/2010: Toshiba A300 Brightness Buttons