I have an HP Pavilion dv6 laptop running Natty. The brightness controls work fine in Windows but never worked in Ubuntu. I finally installed Kamal Mostafa's patch that worked perfectly for a while, and then abruptly stopped working a few months ago. At that point I did something (unfortunately I don't remember what) and got it working again, but then two things happened:
1. My computer kept crashing (maybe once or twice a week for a few weeks) with a "Tainted" message and the name of the backlight patch; I don't remember exactly what the error was, but at the time the backlight controls continued to work so I didn't pay too much attention to it.
2. Today the backlight controls stopped working again altogether, and I can't figure out what to do to fix it-- this is a somewhat more pressing problem for me since my eyes can't take the current screen brightness and no other adjustments have worked. I think it might have to do with an apt-get update/apt-get upgrade I did recently, but I have upgraded before today and it's been fine, so I don't know exactly what might be causing it.
Any help would be very much appreciated.