netbsd man page for acpiout

ACPIVGA(4)						   BSD Kernel Interfaces Manual 						ACPIVGA(4)

NAME
     acpivga -- ACPI Display Adapter and Output Devices

SYNOPSIS
     acpivga* at acpi?
     acpiout* at acpivga?

DESCRIPTION
     The acpivga driver provides generic support for brightness control and output switching, through ACPI video extensions.  The ACPI specifica-
     tion requires that systems containing a built-in display adapter implement these extensions in their ACPI BIOS.

     The driver handles brightness hotkeys and display switch hotkeys.	In addition, the following sysctl(8) read/write variables are provided
     (when hardware support is available):

     hw.acpi.acpivga0.bios_switch
	     BIOS output switching policy.  This boolean variable controls the behavior of the BIOS when a display switch hotkey is pressed.
	     1	  the BIOS should automatically switch outputs, with no interaction from acpivga.
	     0	  the BIOS should only notify acpivga of the desired output state changes.

     hw.acpi.acpiout0.brightness
	     Brightness level.	This integer variable typically ranges from 0 to 100, but any integer value is accepted (the driver uses the clos-
	     est brightness level supported by the device).

     Please note, however, that future versions of acpivga may remove these sysctl(8) variables without prior notice.

SEE ALSO
     acpi(4), vga(4), sysctl(8)

     Microsoft Corporation, Mobile System Displays and Windows, Version 1.2c, http://www.microsoft.com/whdc/archive/mobiledisplay.mspx, December
     4, 2001.

HISTORY
     The acpivga driver appeared in NetBSD 6.0.

AUTHORS
     Gregoire Sutre <gsutre@NetBSD.org>

CAVEATS
     The acpivga driver only supports PCI/PCI-X/PCI-E display adapters.

     Many ACPI BIOSes implement only part of the ACPI video extensions.  In particular, display output switching via these extensions often does
     not work.	For this reason, acpivga enables hw.acpi.acpivga0.bios_switch by default.  If the display switch hotkey does not work with this
     default setting, try setting hw.acpi.acpivga0.bios_switch to 0.

     Brightness level should be controlled via wsconsctl(8) instead of sysctl(8).

BSD
								 October 28, 2010							       BSD