[Intel-gfx] [PATCH v2] drm/i915: Try to guess PCH type even without ISA bridge

[Jani Nikula]

On Fri, 18 Dec 2020, Xiong Zhang <xiong.y.zhang at intel.com> wrote:
> From: Zhenyu Wang <zhenyuw at linux.intel.com>
>
> Some vmm like hyperv and crosvm don't supply any ISA bridge to their guest,
> when igd passthrough is equipped on these vmm, guest i915 display may
> couldn't work as guest i915 detects PCH_NONE pch type.
>
> When i915 runs as guest, this patch guess pch type through gpu type even
> without ISA bridge.
>
> v2: Fix CI warning
>
> Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h  |  7 +++++-
>  drivers/gpu/drm/i915/intel_pch.c | 38 ++++++++++++++++++++++----------
>  2 files changed, 32 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 5a7df5621aa3..df0b8f9268b2 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1758,6 +1758,11 @@ tgl_revids_get(struct drm_i915_private *dev_priv)
>  #define INTEL_DISPLAY_ENABLED(dev_priv) \
>  	(drm_WARN_ON(&(dev_priv)->drm, !HAS_DISPLAY(dev_priv)), !(dev_priv)->params.disable_display)
>  
> +static inline bool run_as_guest(void)
> +{
> +	return !hypervisor_is_type(X86_HYPER_NATIVE);
> +}
> +
>  static inline bool intel_vtd_active(void)
>  {
>  #ifdef CONFIG_INTEL_IOMMU
> @@ -1766,7 +1771,7 @@ static inline bool intel_vtd_active(void)
>  #endif
>  
>  	/* Running as a guest, we assume the host is enforcing VT'd */
> -	return !hypervisor_is_type(X86_HYPER_NATIVE);
> +	return run_as_guest();
>  }
>  
>  static inline bool intel_scanout_needs_vtd_wa(struct drm_i915_private *dev_priv)
> diff --git a/drivers/gpu/drm/i915/intel_pch.c b/drivers/gpu/drm/i915/intel_pch.c
> index f31c0dabd0cc..a73c60bf349e 100644
> --- a/drivers/gpu/drm/i915/intel_pch.c
> +++ b/drivers/gpu/drm/i915/intel_pch.c
> @@ -184,6 +184,23 @@ intel_virt_detect_pch(const struct drm_i915_private *dev_priv)
>  	return id;
>  }
>  
> +static void intel_detect_pch_virt(struct drm_i915_private *dev_priv)
> +{
> +	unsigned short id;
> +	enum intel_pch pch_type;
> +
> +	id = intel_virt_detect_pch(dev_priv);

intel_detect_pch_virt() calls intel_virt_detect_pch()... the naming
should be clarified to make some difference.

> +	pch_type = intel_pch_type(dev_priv, id);
> +
> +	/* Sanity check virtual PCH id */
> +	if (drm_WARN_ON(&dev_priv->drm,
> +			id && pch_type == PCH_NONE))
> +		id = 0;
> +
> +	dev_priv->pch_type = pch_type;
> +	dev_priv->pch_id = id;

Previously the pch type and id assignments were all done in
intel_detect_pch(), so moving this to a separate function in *some* but
not all cases reduces clarity too.

BR,
Jani.

> +}
> +
>  void intel_detect_pch(struct drm_i915_private *dev_priv)
>  {
>  	struct pci_dev *pch = NULL;
> @@ -221,16 +238,7 @@ void intel_detect_pch(struct drm_i915_private *dev_priv)
>  			break;
>  		} else if (intel_is_virt_pch(id, pch->subsystem_vendor,
>  					     pch->subsystem_device)) {
> -			id = intel_virt_detect_pch(dev_priv);
> -			pch_type = intel_pch_type(dev_priv, id);
> -
> -			/* Sanity check virtual PCH id */
> -			if (drm_WARN_ON(&dev_priv->drm,
> -					id && pch_type == PCH_NONE))
> -				id = 0;
> -
> -			dev_priv->pch_type = pch_type;
> -			dev_priv->pch_id = id;
> +			intel_detect_pch_virt(dev_priv);
>  			break;
>  		}
>  	}
> @@ -246,8 +254,14 @@ void intel_detect_pch(struct drm_i915_private *dev_priv)
>  		dev_priv->pch_id = 0;
>  	}
>  
> -	if (!pch)
> -		drm_dbg_kms(&dev_priv->drm, "No PCH found.\n");
> +	if (!pch) {
> +		if (run_as_guest()) {
> +			drm_dbg_kms(&dev_priv->drm, "No PCH found in vm, try guess..\n");
> +			intel_detect_pch_virt(dev_priv);
> +		} else {
> +			drm_dbg_kms(&dev_priv->drm, "No PCH found.\n");
> +		}
> +	}
>  
>  	pci_dev_put(pch);
>  }

-- 
Jani Nikula, Intel Open Source Graphics Center