On Wed, Feb 28, 2018 at 7:32 AM, Alex Hung <alex.hung@xxxxxxxxxxxxx> wrote:
> 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@xxxxxxxxxxxxx>
> ---
> drivers/acpi/osi.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
> index 76998a5..e1a61a7 100644
> --- a/drivers/acpi/osi.c
> +++ b/drivers/acpi/osi.c
> @@ -57,6 +57,8 @@ osi_setup_entries[OSI_STRING_ENTRIES_MAX] __initdata = {
> {"Processor Device", true},
> {"3.0 _SCP Extensions", true},
> {"Processor Aggregator Device", true},
> + /* OEM _OSI strings */
> + {"Linux-Dell-Video", true},
This is a workaround for the kernel's behavior not matching the
expectations of the platform firmware.
You need to add a comment explaining why this _OSI string needs to be
responded to. In particular, what changes need to be made to the
kernel so that it doesn't need to respond to this string in the
future.
> };
>
> static u32 acpi_osi_handler(acpi_string interface, u32 supported)
> --
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