Created attachment 633881 [details] lshw, dmesg, journal, Xorg.0.log On HP Pavilion g6 Notebook PC it looks like a live USB fails to boot. KMS leaves a black display. Googling hints that something has been reversed. It turns out thatadjusting the backlight level with the relevant keys actually works and reveals fine graphics. Booting with i915.invert_brightness=1 solves the problem ... but will probably break other machines. (The direction of up/down was also reversed ... but I don't remember if it was with or without invert_brightness. That is however less of a problem.) I guess this model needs some kind of quirk. It has been discussed elsewhere but apperently never upstreamed: http://unix.stackexchange.com/questions/30580/black-screen-at-boot-with-mint-and-ubuntu-live-cds https://bugs.launchpad.net/ubuntu/+source/linux/+bug/765438 kernel-3.6.2-2.fc18.x86_64 Bugzilla hints that bug 812544 might be related. That is possible - it doesn't provide enough information to know for sure.
It seems to be related to https://bugs.freedesktop.org/show_bug.cgi?id=48435 . One solution seems to be to add a quirk as it is done for Acer Aspire 5734Z in http://www.serverphorums.com/read.php?12,462858,462861#msg-462861 Another (better?) solution seems to be to fix the root cause and remove i915.invert_brightness as proposed in the http://web.archiveorange.com/archive/v/rNRcWpAp3NoK7TDlUdOG thread. 3.7.0-0.rc3.git0.1.fc19.i686.PAEdebug do however still have i915.invert_brightness so the patch must have been forgotten or rejected somewhere / somehow.
Dave, Adam, any preference on which fix to pursue here?
Are you still seeing this with 3.8.x?
I no longer have access to that machine and cannot verify.
OK, thank you for letting us know and sorry for the delay in response. We'll close this out for now. If you or someone else happens to come across a machine like that, please reopen.