ACPI: thinkpad-acpi: allow use of CMOS NVRAM for brightness control
It appears that Lenovo decided to break the EC brightness control interface
in a weird way in their latest BIOSes. Fortunately, the old CMOS NVRAM
interface works just fine in such BIOSes.
Add a module parameter that allows the user to select which strategy to use
for brightness control: EC, NVRAM, or both. By default, do both (which is
the way thinkpad-acpi used to work until now) on IBM ThinkPads, and use
NVRAM only on Lenovo ThinkPads.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 5197f9b..aaaa61e 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -150,6 +150,7 @@
depends on X86 && ACPI
select BACKLIGHT_CLASS_DEVICE
select HWMON
+ select NVRAM
---help---
This is a driver for the IBM and Lenovo ThinkPad laptops. It adds
support for Fn-Fx key combinations, Bluetooth control, video