I installed Debian Jessie on Macbook Pro. Most of the parts working properly. But when I press F1 or F2 key lcd brightness decreased or increased. If I used with while pressing fn key, functions keys works as expected.
Is there a way to change this behaviour to make functions keys works normally?
Yes, you can change this behaviour with giving correct option to kernel module hid_apple. It has a parameter named fnmode which can accept following values:
0 : disable fn key completely
1: use function keys last (with pressing fn)
2: use function keys first
So, using fnmode=2 when loading hid_apple module is what you want.
You can make this setting permanent with creating a modprobe rule in a file for example: /etc/modprobe.d/hid_apple.conf like this:
options hid_apple fnmode=2You can also change the settings in runtime without unloading&loading hid_apple module with:
$ echo 2 | sudo tee /sys/module/hid_apple/parameters/fnmode