Re: [PATCH 11/23] drm/i915: Handle the TCCOLD power-down event

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

On Sat, Jun 08, 2019 at 12:41:10AM +0300, Souza, Jose wrote:
> On Tue, 2019-06-04 at 17:58 +0300, Imre Deak wrote:
> > Based on a recent BSpec update (Index/21750) we must handle the
> > TCCOLD
> > event associated with the DP-alt mode. We can detect this event by
> > reading an invalid all-1s value from FIA registers.
> > 
> > After detecting TCCOLD we will:
> > - fall back to TBT-alt mode when attempting to switch to DP-alt mode
> > - conclude that nothing is connected during live status detection
> > - WARN when already in unsafe mode, since then TCCOLD is unexpected
> > 
> > Cc: José Roberto de Souza <jose.souza@intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_tc.c | 23 +++++++++++++++++++++--
> >  1 file changed, 21 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_tc.c
> > b/drivers/gpu/drm/i915/intel_tc.c
> > index 84e0c06877ec..d91381c0e87d 100644
> > --- a/drivers/gpu/drm/i915/intel_tc.c
> > +++ b/drivers/gpu/drm/i915/intel_tc.c
> > @@ -49,6 +49,8 @@ u32 intel_tc_port_get_lane_info(struct
> > intel_digital_port *dig_port)
> >  	enum tc_port tc_port = intel_port_to_tc(dev_priv, dig_port-
> > >base.port);
> >  	u32 lane_info = I915_READ(PORT_TX_DFLEXDPSP);
> >  
> > +	WARN_ON(lane_info == -1);
> 
> I would use 0xFFFFFFFF, it could cause a warning in some
> compiler(comparing a signed with a unsigned).

Shouldn't cause any compiler warnings, since there is a conversion of
the types to a common type first, which is unsigned int in this case.
That's according to the C standard, so should be fine and it's a short
way to write an all-1s value, whatever is on the other side (u32 now,
but could be for instance u64).

> 
> Other than that:
> Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
> 
> 
> > +
> >  	return (lane_info & DP_LANE_ASSIGNMENT_MASK(tc_port)) >>
> >  	       DP_LANE_ASSIGNMENT_SHIFT(tc_port);
> >  }
> > @@ -107,6 +109,12 @@ static u32 tc_port_live_status_mask(struct
> > intel_digital_port *dig_port)
> >  	u32 val = I915_READ(PORT_TX_DFLEXDPSP);
> >  	u32 mask = 0;
> >  
> > +	if (val == -1) {
> > +		DRM_DEBUG_DRIVER("Port %s: PHY in TCCOLD, nothing
> > connected\n",
> > +				 tc_port_name(dev_priv, tc_port));
> > +		return mask;
> > +	}
> > +
> >  	if (val & TC_LIVE_STATE_TBT(tc_port))
> >  		mask |= BIT(TC_PORT_TBT_ALT);
> >  	if (val & TC_LIVE_STATE_TC(tc_port))
> > @@ -131,13 +139,21 @@ static bool icl_tc_phy_status_complete(struct
> > intel_digital_port *dig_port)
> >  	       DP_PHY_MODE_STATUS_COMPLETED(tc_port);
> >  }
> >  
> > -static void icl_tc_phy_set_safe_mode(struct intel_digital_port
> > *dig_port,
> > +static bool icl_tc_phy_set_safe_mode(struct intel_digital_port
> > *dig_port,
> >  				     bool enable)
> >  {
> >  	struct drm_i915_private *dev_priv = to_i915(dig_port-
> > >base.base.dev);
> >  	enum tc_port tc_port = intel_port_to_tc(dev_priv, dig_port-
> > >base.port);
> >  	u32 val = I915_READ(PORT_TX_DFLEXDPCSSS);
> >  
> > +	if (val == -1) {
> > +		DRM_DEBUG_DRIVER("Port %s: PHY in TCCOLD, can't set
> > safe-mode to %s\n",
> > +				 tc_port_name(dev_priv, tc_port),
> > +				 enableddisabled(enable));
> > +
> > +		return false;
> > +	}
> > +
> >  	val &= ~DP_PHY_MODE_STATUS_NOT_SAFE(tc_port);
> >  	if (!enable)
> >  		val |= DP_PHY_MODE_STATUS_NOT_SAFE(tc_port);
> > @@ -147,6 +163,8 @@ static void icl_tc_phy_set_safe_mode(struct
> > intel_digital_port *dig_port,
> >  	if (enable && wait_for(!icl_tc_phy_status_complete(dig_port),
> > 10))
> >  		DRM_DEBUG_DRIVER("Port %s: PHY complete clear timed
> > out\n",
> >  				 tc_port_name(dev_priv, tc_port));
> > +
> > +	return true;
> >  }
> >  
> >  /*
> > @@ -187,7 +205,8 @@ static bool icl_tc_phy_connect(struct
> > intel_digital_port *dig_port)
> >  		return false;
> >  	}
> >  
> > -	icl_tc_phy_set_safe_mode(dig_port, false);
> > +	if (!icl_tc_phy_set_safe_mode(dig_port, false))
> > +		return false;
> >  
> >  	if (dig_port->tc_mode == TC_PORT_LEGACY)
> >  		return true;
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