Once I upgraded to the Ubuntu mainline kernel 3.9.0-030900-generic, my laptop keyboard backlight won’t go off in certain lighting conditions even if I am not typing anything. So I decided to turn it off completely till the synaptic kernel version catches up. To do this, append the following in GRUB_CMDLINE_LINUX_DEFAULT of /etc/default/grub on Ubuntu 13.04:
sony_laptop.kbd_backlight=0The problem is now fixed, but it’s surprising. I added the following in /etc/default/grub:
sony_laptop.kbd_backlight_timeout=1
timeout=0 means 10 seconds and that’s the default. But it doesn’t seem to work on the mainline kernel. timeout=1 works as expected.
Some useful links:
TuxDiary 
Quite a complicated process! But I asked Sony direct and they don’t know how to do it! The clear message is don’t buy Sony laptops.
Sony is experiencing doomsday anyway ;)… I got it at a low budget from another guy, so had to tame it to Ubuntu :).