Re: [PATCH 3/5] drm/i915/bxt: Added _DSM call to set HPD_CTL.

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Nov 23, 2016 at 09:48:25PM +0530, Animesh Manna wrote:
> _DSM is added to program HPD_CTL(0x1094) register
> of PMC from i915 driver which will be called
> based on driver feature flag. PMC hpd control register
> programming will enable PMC to get hpd interrupt
> during dc9.
> 
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_acpi.c | 44 ++++++++++++++++++++++++++++++++-------
>  1 file changed, 37 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_acpi.c b/drivers/gpu/drm/i915/intel_acpi.c
> index 8c878ab..15d3b84 100755
> --- a/drivers/gpu/drm/i915/intel_acpi.c
> +++ b/drivers/gpu/drm/i915/intel_acpi.c
> @@ -10,6 +10,8 @@
>  
>  #define INTEL_DSM_REVISION_ID 1 /* For Calpella anyway... */
>  #define INTEL_DSM_FN_PLATFORM_MUX_INFO 1 /* No args */
> +#define INTEL_DSM_SET_HPD_WAKEUP 17
> +#define HPD_WAKEUP_EN_VAL 0xFCF0
>  
>  static struct intel_dsm_priv {
>  	acpi_handle dhandle;
> @@ -118,6 +120,25 @@ static void intel_dsm_platform_mux_info(void)
>  	ACPI_FREE(pkg);
>  }
>  
> +static void intel_dsm_set_hpd_wakeup(u8 *guid)
> +{
> +	union acpi_object *obj;
> +	union acpi_object argv4 = {
> +		.integer.type = ACPI_TYPE_INTEGER,
> +		.integer.value = HPD_WAKEUP_EN_VAL,
> +	};
> +
> +	obj = acpi_evaluate_dsm_typed(intel_dsm_priv.dhandle, guid,
> +			INTEL_DSM_REVISION_ID, INTEL_DSM_SET_HPD_WAKEUP,
> +			&argv4, ACPI_TYPE_INTEGER);
> +
> +	if (!obj)
> +		DRM_DEBUG_DRIVER("failed to evaluate _DSM\n");
> +
> +	ACPI_FREE(obj);
> +}
> +
> +
>  static bool intel_dsm_pci_probe(struct pci_dev *pdev)
>  {
>  	acpi_handle dhandle;
> @@ -134,14 +155,23 @@ static bool intel_dsm_pci_probe(struct pci_dev *pdev)
>  	else
>  		guid = intel_dsm_guid;
>  
> -	if (!acpi_check_dsm(dhandle, guid, INTEL_DSM_REVISION_ID,
> -			    1 << INTEL_DSM_FN_PLATFORM_MUX_INFO)) {
> -		DRM_DEBUG_KMS("no _DSM method for intel device\n");
> -		return false;
> -	}
> -
>  	intel_dsm_priv.dhandle = dhandle;
> -	intel_dsm_platform_mux_info();
> +
> +	if (acpi_check_dsm(dhandle, guid, INTEL_DSM_REVISION_ID,
> +				1 << INTEL_DSM_FN_PLATFORM_MUX_INFO))
> +		intel_dsm_platform_mux_info();
> +	else
> +		DRM_DEBUG_KMS("no _DSM method for mux-info\n");
> +
> +	/* Need to ensure vbt parsing is completed. */

Eh?

> +	if (dev_priv->vbt.hpd_wakeup_enabled &&
> +		acpi_check_dsm(dhandle, guid, INTEL_DSM_REVISION_ID,
> +				1 << INTEL_DSM_SET_HPD_WAKEUP))
> +		intel_dsm_set_hpd_wakeup(guid);

So we're permanently routing hpds to the pcu? Won't that mess up
stuff like short pulse detection?

I was expecting that we'd switch between the PCU and not during
runtime suspend/resume.

> +	else {
> +		dev_priv->vbt.hpd_wakeup_enabled = false;
> +		DRM_DEBUG_KMS("no _DSM method for hpd-enabling\n");
> +	}
>  
>  	return true;
>  }
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC
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