I'm working on a little mini-project that deals with back-light.
I've read the kernel documentation I could find , , ,  and I poked all my systems to see what values are produced. I only have a number of intel and intel/nvidia systems. I don't have any AMD portables at home. I would really like to see how they behave.
Towards that end I wrote a little tool that collects the most common properties (type and brigthness ranges) and dumps that to a tarball, along with the output of uname, lspci and a few others (nothing sensitive or personally-identifiable though). You can grab the tool from .
If you want to help me out please run the script and send the results to my email address at zygmunt<dot>krynicki<at>canonical.com.