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Commit 887532ca authored by Alex Hung's avatar Alex Hung Committed by Rafael J. Wysocki
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ACPI / OSI: Add OEM _OSI string to enable NVidia HDMI audio 



Some ThinkPad systems have a power-saving feature that turns off HDMI
audio device in Windows, but NVidia Linux driver does not support this
feature. As a result, HDMI audio will not work on Linux.

A BIOS workaround is added with an OEM_OSI string
"Linux-Lenovo-NV-HDMI-Audio" to power on NVidia HDMI audio when booting.

The form of the OEM _OSI strings is defined by each OEMs and is
discussed in Documentation/acpi/osi.txt.

Signed-off-by: default avatarAlex Hung <alex.hung@canonical.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 9d3cce1e

drivers/acpi/osi.c

+8 −0
Original line number Diff line number Diff line
@@ -66,6 +66,14 @@ osi_setup_entries[OSI_STRING_ENTRIES_MAX] __initdata = { 
	 * be removed if both new and old graphics cards are supported.

	 */

	{"Linux-Dell-Video", true},

	/*

	 * Linux-Lenovo-NV-HDMI-Audio is used by BIOS to power on NVidia's HDMI

	 * audio device which is turned off for power-saving in Windows OS.

	 * This power management feature observed on some Lenovo Thinkpad

	 * systems which will not be able to output audio via HDMI without

	 * a BIOS workaround.

	 */

	{"Linux-Lenovo-NV-HDMI-Audio", true},

};



static u32 acpi_osi_handler(acpi_string interface, u32 supported)