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

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Message-ID: <87leror4sl.fsf@intel.com>
Date:   Tue, 16 Aug 2022 11:06:18 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        joonas.lahtinen@...ux.intel.com, rodrigo.vivi@...el.com,
        tvrtko.ursulin@...ux.intel.com
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>, Zenghui Yu <yuzenghui@...wei.com>,
        Lyude Paul <lyude@...hat.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/i915: Switch TGL-H DP-IN to dGFX when it's supported

On Tue, 16 Aug 2022, Kai-Heng Feng <kai.heng.feng@...onical.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@...onical.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