From 887532ca7ca59fcf0547a79211756791128030a3 Mon Sep 17 00:00:00 2001 From: Alex Hung Date: Wed, 18 Jul 2018 11:46:55 -0700 Subject: 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: Alex Hung Signed-off-by: Rafael J. Wysocki --- drivers/acpi/osi.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers') diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c index 8a8f43568510..b2a16ed7e81a 100644 --- a/drivers/acpi/osi.c +++ b/drivers/acpi/osi.c @@ -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) -- cgit v1.2.3-59-g8ed1b