https://bugzilla.kernel.org/show_bug.cgi?id=48941
--- Comment #6 from Igor Murzov e-mail@date.by 2012-10-19 15:16:21 --- The patch fixed the issue. I have two bl devices now: # tree /sys/class/backlight/ /sys/class/backlight/ ├── radeon_bl0 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:05.0/drm/card0/card0-LVDS-1/radeon_bl0 └── radeon_bl1 -> ../../devices/pci0000:00/0000:00:02.0/0000:02:00.0/drm/card1/card1-LVDS-2/radeon_bl1