From efaa14c7e981bdf8d3c8d39d3ed12bdc60faabb8 Mon Sep 17 00:00:00 2001 From: Aaron Lu Date: Tue, 16 Jul 2013 13:08:05 +0800 Subject: [PATCH] ACPI / video: no automatic brightness changes by win8-compatible firmware 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 Reported-by: Dan Garton Reported-by: Bob Ziuchkovski Signed-off-by: Aaron Lu Signed-off-by: Rafael J. Wysocki --- Reading git-format-patch failed