https://bugs.freedesktop.org/show_bug.cgi?id=83460

Priority: medium Bug ID: 83460 Assignee: dri-devel@lists.freedesktop.org Summary: [radeon regression] Backlight turned off since kernel upgrade Severity: normal Classification: Unclassified OS: Linux (All) Reporter: spmf2004-freedesktop@yahoo.fr Hardware: x86-64 (AMD64) Status: NEW Version: XOrg CVS Component: DRM/Radeon Product: DRI

Since the upgrade to Ubuntu kernel 3.13.0-35 (from 3.13.0-34), the screen is very dark to the point it's unusable. Backlight seems completely turned off. Using the brightness keys doesn't help. It was working fine with 3.13.0-34. I found that the offending patch is "drm/radeon: set default bl level to something reasonable". I reverted this patch and recompiled 3.13.0-35, and it solved the problem. I also checked that this problem also affects mainline kernel 3.17rc3. More technical details can be found on Ubuntu's bugtracker : https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1364148