Currently we disable the Acer WMI backlight device if there is no ACPI backlight device. As a result, we end up with no backlight device at all. We should instead disable it if there is an ACPI device, as the other laptop drivers do. This regression was introduced infebf2d9("Acer-WMI: fingers off backlight if video.ko is serving this functionality"). Each laptop driver with backlight support got a similar change aroundfebf2d9. The changes to the other drivers look correct; see e.g.a598c82ffor a similar but correct change. The regression is also in 2.6.28. Signed-off-by: Michael Spang <mspang@csclub.uwaterloo.ca> Acked-by: Thomas Renninger <trenn@suse.de> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Carlos Corbacho <carlos@strangeworlds.co.uk> Cc: Len Brown <len.brown@intel.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: <stable@kernel.org> [2.6.28.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>