https://github.com/torvalds/linux
Revision efaa14c7e981bdf8d3c8d39d3ed12bdc60faabb8 authored by Aaron Lu on 16 July 2013, 05:08:05 UTC, committed by Rafael J. Wysocki on 18 July 2013, 00:08:16 UTC
Starting from win8, MS backlight control driver will set bit 2 of the
parameter of control method _DOS, to inform firmware it should not
perform any automatic brightness changes. This mostly affects hotkey
notification deliver - if we do not set this bit, on hotkey press,
firmware may choose to adjust brightness level instead of sending out
notification and doing nothing.

So this patch sets bit 2 when calling _DOS so that GUIs can show the
notification window on hotkey press.  This behavior change is only
necessary for win8 systems.

The MS document on win8 backlight control is here:
http://msdn.microsoft.com/en-US/library/windows/hardware/jj159305

References: https://bugzilla.kernel.org/show_bug.cgi?id=52951
References: https://bugzilla.kernel.org/show_bug.cgi?id=56711
Reported-by: Micael Dias <kam1kaz3@gmail.com>
Reported-by: Dan Garton <dan.garton@gmail.com>
Reported-by: Bob Ziuchkovski <bob.ziuchkovski@gmail.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
1 parent 8c5bd7a
History
Tip revision: efaa14c7e981bdf8d3c8d39d3ed12bdc60faabb8 authored by Aaron Lu on 16 July 2013, 05:08:05 UTC
ACPI / video: no automatic brightness changes by win8-compatible firmware
Tip revision: efaa14c
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.gitignore -rw-r--r-- 1.1 KB
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COPYING -rw-r--r-- 18.3 KB
CREDITS -rw-r--r-- 93.1 KB
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Kconfig -rw-r--r-- 252 bytes
MAINTAINERS -rw-r--r-- 253.4 KB
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