Re: [PATCH] drm/i915: Switch TGL-H DP-IN to dGFX when it's supported

Jani Nikula
2022-08-16T09:39:31Z

On Tue, 16 Aug 2022, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
> On mobile workstations like HP ZBook Fury G8, iGFX's DP-IN can switch to
> dGFX so external monitors are routed to dGFX, and more monitors can be
> supported as result.
>
> To switch the DP-IN to dGFX, the driver needs to invoke _DSM function 20
> on intel_dsm_guid2. This method is described in Intel document 632107.

Is this the policy decision that we want to unconditionally make,
though?

BR,
Jani.

>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
> drivers/gpu/drm/i915/display/intel_acpi.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_acpi.c b/drivers/gpu/drm/i915/display/intel_acpi.c
> index e78430001f077..3bd5930e2769b 100644
> --- a/drivers/gpu/drm/i915/display/intel_acpi.c
> +++ b/drivers/gpu/drm/i915/display/intel_acpi.c
> @@ -20,6 +20,7 @@ static const guid_t intel_dsm_guid =
> 0xa8, 0x54, 0x0f, 0x13, 0x17, 0xb0, 0x1c, 0x2c);
>
> #define INTEL_DSM_FN_GET_BIOS_DATA_FUNCS_SUPPORTED 0 /* No args */
> +#define INTEL_DSM_FN_DP_IN_SWITCH_TO_DGFX 20 /* No args */
>
> static const guid_t intel_dsm_guid2 =
> GUID_INIT(0x3e5b41c6, 0xeb1d, 0x4260,
> @@ -187,6 +188,7 @@ void intel_dsm_get_bios_data_funcs_supported(struct drm_i915_private *i915)
> struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
> acpi_handle dhandle;
> union acpi_object *obj;
> + int supported = 0;
>
> dhandle = ACPI_HANDLE(&pdev->dev);
> if (!dhandle)
> @@ -194,8 +196,22 @@ void intel_dsm_get_bios_data_funcs_supported(struct drm_i915_private *i915)
>
> obj = acpi_evaluate_dsm(dhandle, &intel_dsm_guid2, INTEL_DSM_REVISION_ID,
> INTEL_DSM_FN_GET_BIOS_DATA_FUNCS_SUPPORTED, NULL);
> - if (obj)
> + if (obj) {
> + if (obj->type == ACPI_TYPE_INTEGER)
> + supported = obj->integer.value;
> +
> ACPI_FREE(obj);
> + }
> +
> + /* Tiger Lake H DP-IN Boot Time Switching from iGfx to dGfx */
> + if (supported & BIT(20)) {
> + obj = acpi_evaluate_dsm(dhandle, &intel_dsm_guid2,
> + INTEL_DSM_REVISION_ID,
> + INTEL_DSM_FN_DP_IN_SWITCH_TO_DGFX,
> + NULL);
> + if (obj)
> + ACPI_FREE(obj);
> + }
> }
>
> /*

--
Jani Nikula, Intel Open Source Graphics Center