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

Kai-Heng Feng
2022-08-16T11:54:06Z

On Tue, Aug 16, 2022 at 4:06 PM Jani Nikula <jani.nikula@linux.intel.com> wrote:
>
> 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?

I believes so, so more external monitors can be supported at the same time.

Kai-Heng

>
> 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