From 24d3b77467b6aaf59e38dce4aa86d05541858195 Mon Sep 17 00:00:00 2001 From: Henrique de Moraes Holschuh Date: Wed, 18 Jul 2007 23:45:43 -0300 Subject: 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 Signed-off-by: Len Brown --- Documentation/thinkpad-acpi.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation/thinkpad-acpi.txt') diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt index c670363cf5a4..c145bcce2339 100644 --- a/Documentation/thinkpad-acpi.txt +++ b/Documentation/thinkpad-acpi.txt @@ -860,6 +860,12 @@ cannot be controlled. The backlight control has eight levels, ranging from 0 to 7. Some of the levels may not be distinct. +There are two interfaces to the firmware for brightness control, EC and CMOS. +To select which one should be used, use the brightness_mode module parameter: +brightness_mode=1 selects EC mode, brightness_mode=2 selects CMOS mode, +brightness_mode=3 selects both EC and CMOS. The driver tries to autodetect +which interface to use. + Procfs notes: The available commands are: -- cgit v1.2.1