ACK: [PATCH 1/1][SRU][Bionic] ACPI / OSI: Add OEM _OSI strings to disable NVidia RTD3

[Kleber Souza]

On 05/27/18 20:29, Alex Hung wrote:
> BugLink: https://bugs.launchpad.net/bugs/1773299
> 
> A number of Dell systems require an OEM _OSI string "Linux-Dell-Video"
> as a BIOS workaround to disable RTD3 which causes systems hangs when
> NVidia graphics cards are installed.  The affected Dell systems are
> with system IDs: 0818, 0819, 0820, 0850, 0851, 086F, 0870, 0885 and
> 0886.
> 
> 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 9251a71db62ca9cc7e7cf364218610b0f018c291)
> Signed-off-by: Alex Hung <alex.hung at canonical.com>

Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>

> ---
>  drivers/acpi/osi.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
> index c2ef3e6c21ba..081e25e66e1c 100644
> --- a/drivers/acpi/osi.c
> +++ b/drivers/acpi/osi.c
> @@ -57,6 +57,15 @@ osi_setup_entries[OSI_STRING_ENTRIES_MAX] __initdata = {
>  	{"Processor Device", true},
>  	{"3.0 _SCP Extensions", true},
>  	{"Processor Aggregator Device", true},
> +	/*
> +	 * Linux-Dell-Video is used by BIOS to disable RTD3 for NVidia graphics
> +	 * cards as RTD3 is not supported by drivers now.  Systems with NVidia
> +	 * cards will hang without RTD3 disabled.
> +	 *
> +	 * Once NVidia drivers officially support RTD3, this _OSI strings can
> +	 * be removed if both new and old graphics cards are supported.
> +	 */
> +	{"Linux-Dell-Video", true},
>  };
>  
>  static u32 acpi_osi_handler(acpi_string interface, u32 supported)
>