After modprobing i2c-dev, you need to /etc/init.d/pbbuttonsd restart too...If you run powerprefs you should see that the Keyboard Illumination tabs are activated. If the tabs are greyed out it means pbbuttonsd doesn't see that you have a backlight available.
It might be worth checking your kernel options if this is the case - after playing around for a while trying to trim my kernel down and trying to get keyboard illumination to work on my 5,4, I just enabled (as modules) all the options under I2C (Devices --> Character Devices) except the debugging stuff, and it worked fine. I think the most important options are I2C_DEV and the CHRP Device support options, but just put all of them in as there are other dependencies too, but I'm not sure what they are.
Unless it starts working after a restart of pbbuttonsd, this is probably what you need to do. I did not have to mknod the i2c device btw: this should happen automatically if your kernel is correctly configured.
You can then add i2c_dev to your /etc/modules to have it load on boot automagically.
Erik Quoting Marco Stagno <marco.stagno@libero.it>:
the module i2c-dev is loaded but not used by anyone...You might need i2c-powermac, too.I have it too, but, as i2c-dev, the modules is not used :( I also made /dev/i2c-4 (as I found somewhere in the web), but the keyboard backlight still does't work... thank you MAS! -- To UNSUBSCRIBE, email to debian-powerpc-REQUEST@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org