ACK: [PATCH 1/1] ACPI / OSI: Add OEM _OSI string to enable NVidia HDMI audio

[Shrirang Bagul]

On Tue, 2018-08-14 at 20:18 -0700, Alex Hung wrote:
> BugLink: https://bugs.launchpad.net/bugs/1787058
> 
> 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 at canonical.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
> (cherry picked from commit 887532ca7ca59fcf0547a79211756791128030a3)
> Signed-off-by: Alex Hung <alex.hung at canonical.com>

Acked-by: Shrirang Bagul <shrirang.bagul at canonical.com>

> ---
>  drivers/acpi/osi.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
> index 081e25e66e1c..e83297ed4ff9 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)
> -- 
> 2.17.1
> 
> 
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