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

[Zhang, Xiong Y]

> 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.
[Zhang, Xiong Y] Indeed the naming is confusing. How about deleting this new added function, then move intel_pch_type() calling into original intel_virt
> 
> > +	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