Re: [PATCH 6/6] drm/i915/bxt: Sanitiy check the PHY lane power down status

[Imre Deak <imre.deak@intel.com>]

On ke, 2016-06-08 at 17:19 +0300, Ville Syrjälä wrote:
> On Tue, Jun 07, 2016 at 09:24:33PM +0300, Imre Deak wrote:
> > We can check the power state of the PHY data and common lanes as
> > reported by the PHY. Do this in case we need to debug problems where the
> > PHY gets stuck in an unexpected state.
> > 
> > Note that I only check these when the lanes are expected to be powered
> > on purpose, since it's not clear at what point the PHY power/clock gates
> > things.
> > 
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_reg.h  |  9 +++++++++
> >  drivers/gpu/drm/i915/intel_ddi.c | 27 +++++++++++++++++++++++++++
> >  2 files changed, 36 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 81fc498..e904818 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -1276,6 +1276,15 @@ enum skl_disp_power_wells {
> >  #define BXT_P_CR_GT_DISP_PWRON		_MMIO(0x138090)
> >  #define   GT_DISPLAY_POWER_ON(phy)	(1 << (phy))
> >  
> > +#define _BXT_PHY_CTL_DDI_A		0x64C00
> > +#define _BXT_PHY_CTL_DDI_B		0x64C10
> > +#define _BXT_PHY_CTL_DDI_C		0x64C20
> > +#define   BXT_PHY_CMNLANE_POWERDOWN_ACK	(1 << 10)
> > +#define   BXT_PHY_LANE_POWERDOWN_ACK	(1 << 9)
> > +#define   BXT_PHY_LANE_ENABLED		(1 << 8)
> > +#define BXT_PHY_CTL(port)		_MMIO_PORT(port, _BXT_PHY_CTL_DDI_A, \
> > +							 _BXT_PHY_CTL_DDI_B)
> > +
> >  #define _PHY_CTL_FAMILY_EDP		0x64C80
> >  #define _PHY_CTL_FAMILY_DDI		0x64C90
> >  #define   COMMON_RESET_DIS		(1 << 31)
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > index acf0a7a..afa28a1 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -1342,6 +1342,16 @@ bool intel_ddi_get_hw_state(struct intel_encoder *encoder,
> >  	DRM_DEBUG_KMS("No pipe for ddi port %c found\n", port_name(port));
> >  
> >  out:
> > +	if (ret && IS_BROXTON(dev_priv)) {
> > +		tmp = I915_READ(BXT_PHY_CTL(port));
> > +		if ((tmp & (BXT_PHY_LANE_POWERDOWN_ACK |
> > +			    BXT_PHY_LANE_ENABLED)) != BXT_PHY_LANE_ENABLED) {
> > +			DRM_DEBUG_KMS("Port %c enabled but PHY powered down? "
> > +				      "(PHY_CTL %08x)\n", port_name(port), tmp);
> > +			ret = false;
> 
> Hmm. I'm not sure I'd change the return value here because then we'd
> fail to follow the proper shutdown sequence, perhaps even messing
> up the next modeset?

What I wanted is to force a reprogramming in this case, but yea we
would miss then the proper disable sequence. AFAICS we can't mark the
state here as enabled but not valid, so for now I will just change the
above to DRM_ERROR then and report an enabled state as you suggested.

> So maybe just ERROR/WARN in these cases?
> 
> > +		}
> > +	}
> > +
> >  	intel_display_power_put(dev_priv, power_domain);
> >  
> >  	return ret;
> > @@ -1745,6 +1755,8 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder)
> >  bool bxt_ddi_phy_is_enabled(struct drm_i915_private *dev_priv,
> >  			    enum dpio_phy phy)
> >  {
> > +	enum port port;
> > +
> >  	if (!(I915_READ(BXT_P_CR_GT_DISP_PWRON) & GT_DISPLAY_POWER_ON(phy)))
> >  		return false;
> >  
> > @@ -1770,6 +1782,21 @@ bool bxt_ddi_phy_is_enabled(struct drm_i915_private *dev_priv,
> >  		return false;
> >  	}
> >  
> > +	for_each_port_masked(port,
> > +			     phy == DPIO_PHY0 ? BIT(PORT_B) | BIT(PORT_C) :
> > +					        BIT(PORT_A)) {
> > +		u32 tmp = I915_READ(BXT_PHY_CTL(port));
> > +
> > +		if (tmp & BXT_PHY_CMNLANE_POWERDOWN_ACK) {
> > +			DRM_DEBUG_DRIVER("DDI PHY %d powered, but common lane "
> > +					 "for port %c powered down "
> > +					 "(PHY_CTL %08x)\n",
> > +					 phy, port_name(port), tmp);
> > +
> > +			return false;
> > +		}
> > +	}
> > +
> >  	return true;
> >  }
> >  
> > -- 
> > 2.5.0
> > 
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> 
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