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authorAlex Hung <alex.hung@canonical.com>2018-07-18 11:46:55 -0700
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-07-20 10:12:41 +0200
commit887532ca7ca59fcf0547a79211756791128030a3 (patch)
tree2946ce1cc669c3e7ef15b2884a59b1502cfc049a /drivers/acpi/osi.c
parent9d3cce1e8b8561fed5f383d22a4d6949db4eadbe (diff)
downloadlinux-887532ca7ca59fcf0547a79211756791128030a3.tar.bz2
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 <alex.hung@canonical.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/osi.c')
-rw-r--r--drivers/acpi/osi.c8
1 files changed, 8 insertions, 0 deletions
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)