I have ubuntu 12.04 lts running on my sony vaio E-series (vpceb44en). I have followed the post How to permanently set screen brightness level in Ubuntu 12.04 on Dell Vostro 2420 laptop? on howto address the issue. It didn't work in my case as after reboot the screen brightness goes to default maximum. Even tried with third party xbacklight, didn't work either. I have Radeon hd5470 card on my machine.