Christopher, I did not try a release before saucy, as the macbook uses haswell processors which seamed not to be supported on raring. The issue is also under discussion on https://bugs.freedesktop.org/show_bug.cgi?id=67454 but without much progress so far.
** Bug watch added: freedesktop.org Bugzilla #67454 https://bugs.freedesktop.org/show_bug.cgi?id=67454 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1241982 Title: [MacBookAir6,2] LED-Panel Brightness not adjustable after suspend/resume To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1241982/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
