UBUNTU: SAUCE: (no-up) ACPI: Disable Windows 8 compatibility for some Lenovo ThinkPads
The AML implementation for brightness control on several ThinkPads
contains a workaround to meet a Windows 8 requirement of 101 brightness
levels [1]. The implementation is flawed, as only 16 of the brighness
values reported by _BCL affect a change in brightness. _BCM silently
discards the rest of the values. Disabling Windows 8 compatibility on
these machines reverts them to the old behavior, making _BCL only report
the 16 brightness levels which actually work. Add a quirk to do this
along with a dmi callback to disable Win8 compatibility.
[1] http://msdn.microsoft.com/en-us/library/windows/hardware/jj128256.aspx
BugLink: http://bugs.launchpad.net/bugs/1183856
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>