A kernel module that enables you to call parameterless ACPI methods by writing
the method name to /proc/acpi/call, e.g. to turn off discrete graphics card in
a dual graphics environment (like NVIDIA Optimus).

Usage:

# turn off discrete graphics card
echo '\_SB.PCI0.PEG1.GFX0.DOFF' > /proc/acpi/call
# turn it back on
echo '\_SB.PCI0.PEG1.GFX0.DON' > /proc/acpi/call

These work on my ASUS K52J notebook, but may not work for you. For a list of
methods to try, see http://linux-hybrid-graphics.blogspot.com/ . It SHOULD be
ok to test all of the methods, until you see a drop in battery drain rate
(grep rate /proc/acpi/battery/BAT0/state), however it comes with NO WARRANTY.

The status after a call can be read back from /proc/acpi/call:
* 'not called' - nothing to report
* 'Error: <description>' - the call failed
* '0xNN' - the call succeeded, and returned an integer
* '"..."' - the call succeeded, and returned a string
* '{0xNN, ...}' - the call succeeded, and returned a buffer


Copyright (c) 2010: Michal Kottman

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.