Re: [PATCH v2 12/23] drm/i915: Sanitize the TypeC connect/detect sequences

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

On Thu, Jun 27, 2019 at 02:55:21AM +0300, Souza, Jose wrote:
> On Thu, 2019-06-20 at 17:05 +0300, Imre Deak wrote:
> > Make the order during detection more consistent: first reset the
> > TypeC
> > port mode if needed (adding new helpers for this), then detect any
> > connected sink.
> > 
> > To check if a port mode reset is needed determine first the target
> > port
> > mode based on the live status if a sink is already connected or the
> > PHY status complete flag otherwise.
> > 
> > Add a WARN in legacy mode if unexpectedly we can't set the unsafe
> > mode
> > or if the FIA doesn't provide the 4 lanes required.
> > 
> > Cc: José Roberto de Souza <jose.souza@intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_tc.c | 96 ++++++++++++-----------
> > --
> >  1 file changed, 47 insertions(+), 49 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_tc.c
> > b/drivers/gpu/drm/i915/display/intel_tc.c
> > index fffe4c4a6602..ed2253b21b09 100644
> > --- a/drivers/gpu/drm/i915/display/intel_tc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> > @@ -172,41 +172,43 @@ static bool icl_tc_phy_set_safe_mode(struct
> > intel_digital_port *dig_port,
> >   * will require a lot of coordination with user space and thorough
> > testing for
> >   * the extra possible cases.
> >   */
> > -static bool icl_tc_phy_connect(struct intel_digital_port *dig_port)
> > +static void icl_tc_phy_connect(struct intel_digital_port *dig_port)
> >  {
> > -	u32 live_status_mask;
> > -
> > -	if (dig_port->tc_mode != TC_PORT_LEGACY &&
> > -	    dig_port->tc_mode != TC_PORT_DP_ALT)
> > -		return true;
> > -
> >  	if (!icl_tc_phy_status_complete(dig_port)) {
> >  		DRM_DEBUG_KMS("Port %s: PHY not ready\n",
> >  			      dig_port->tc_port_name);
> > -		WARN_ON(dig_port->tc_legacy_port);
> > -		return false;
> > +		goto out_set_tbt_alt_mode;
> >  	}
> >  
> > -	if (!icl_tc_phy_set_safe_mode(dig_port, false))
> > -		return false;
> > +	if (!icl_tc_phy_set_safe_mode(dig_port, false) &&
> > +	    !WARN_ON(dig_port->tc_legacy_port))
> > +		goto out_set_tbt_alt_mode;
> 
> Marking as not safe even for TBT?

You mean if the above will set not-safe mode even for TBT? No, we
will try to set not-safe mode only for DP-alt and legacy as the PHY
status complete flag was set.

> 
> >  
> > -	if (dig_port->tc_mode == TC_PORT_LEGACY)
> > -		return true;
> > +	if (dig_port->tc_legacy_port) {
> > +		WARN_ON(intel_tc_port_fia_max_lane_count(dig_port) !=
> > 4);
> > +		dig_port->tc_mode = TC_PORT_LEGACY;
> >  
> > -	live_status_mask = tc_port_live_status_mask(dig_port);
> > +		return;
> > +	}
> >  
> >  	/*
> >  	 * Now we have to re-check the live state, in case the port
> > recently
> >  	 * became disconnected. Not necessary for legacy mode.
> >  	 */
> > -	if (!(live_status_mask & BIT(TC_PORT_DP_ALT))) {
> > +	if (!(tc_port_live_status_mask(dig_port) &
> > BIT(TC_PORT_DP_ALT))) {
> >  		DRM_DEBUG_KMS("Port %s: PHY sudden disconnect\n",
> >  			      dig_port->tc_port_name);
> > -		icl_tc_phy_disconnect(dig_port);
> > -		return false;
> > +		goto out_set_safe_mode;
> >  	}
> >  
> > -	return true;
> > +	dig_port->tc_mode = TC_PORT_DP_ALT;
> > +
> > +	return;
> > +
> > +out_set_safe_mode:
> > +	icl_tc_phy_set_safe_mode(dig_port, true);
> > +out_set_tbt_alt_mode:
> > +	dig_port->tc_mode = TC_PORT_TBT_ALT;
> >  }
> >  
> >  /*
> > @@ -227,27 +229,37 @@ void icl_tc_phy_disconnect(struct
> > intel_digital_port *dig_port)
> >  	default:
> >  		MISSING_CASE(dig_port->tc_mode);
> >  	}
> > +}
> >  
> > -	DRM_DEBUG_KMS("Port %s: mode %s disconnected\n",
> > -		      dig_port->tc_port_name,
> > -		      tc_port_mode_name(dig_port->tc_mode));
> > +static enum tc_port_mode
> > +intel_tc_port_get_target_mode(struct intel_digital_port *dig_port)
> > +{
> > +	u32 live_status_mask = tc_port_live_status_mask(dig_port);
> > +
> > +	if (live_status_mask)
> > +		return fls(live_status_mask) - 1;
> > +
> > +	return icl_tc_phy_status_complete(dig_port) &&
> > +	       dig_port->tc_legacy_port ? TC_PORT_LEGACY :
> > +					  TC_PORT_TBT_ALT;
> 
> You are right about the order that C will execute this but could you
> add a pair of parenthesis around icl_tc_phy_status_complete(dig_port)
> && dig_port->tc_legacy_port to make easier to read?

Not sure, I think the use of 'a && b ? c : d' without parens is usual
enough, but maybe others have a better idea for a rule-of-thumb for
using parens that we should follow everywhere. Jani?

Anyway the following would be easier to read (also we can avoid the reg
read for the !legacy case):

	if (dig_port->tc_legacy_port &&
	    icl_tc_phy_status_complete(dig_port))
		return TC_PORT_LEGACY;

	return TC_PORT_TBT_ALT;

> 
> >  }
> >  
> > -static void icl_update_tc_port_type(struct drm_i915_private
> > *dev_priv,
> > -				    struct intel_digital_port
> > *intel_dig_port,
> > -				    u32 live_status_mask)
> > +static void intel_tc_port_reset_mode(struct intel_digital_port
> > *dig_port)
> >  {
> > -	enum tc_port_mode old_mode = intel_dig_port->tc_mode;
> > +	enum tc_port_mode old_tc_mode = dig_port->tc_mode;
> >  
> > -	if (!live_status_mask)
> > -		return;
> > +	icl_tc_phy_disconnect(dig_port);
> > +	icl_tc_phy_connect(dig_port);
> >  
> > -	intel_dig_port->tc_mode = fls(live_status_mask) - 1;
> > +	DRM_DEBUG_KMS("Port %s: TC port mode reset (%s -> %s)\n",
> > +		      dig_port->tc_port_name,
> > +		      tc_port_mode_name(old_tc_mode),
> > +		      tc_port_mode_name(dig_port->tc_mode));
> > +}
> >  
> > -	if (old_mode != intel_dig_port->tc_mode)
> > -		DRM_DEBUG_KMS("Port %s: port has mode %s\n",
> > -			      intel_dig_port->tc_port_name,
> > -			      tc_port_mode_name(intel_dig_port-
> > >tc_mode));
> > +static bool intel_tc_port_needs_reset(struct intel_digital_port
> > *dig_port)
> > +{
> > +	return intel_tc_port_get_target_mode(dig_port) != dig_port-
> > >tc_mode;
> >  }
> >  
> >  /*
> > @@ -262,24 +274,10 @@ static void icl_update_tc_port_type(struct
> > drm_i915_private *dev_priv,
> >   */
> >  bool intel_tc_port_connected(struct intel_digital_port *dig_port)
> >  {
> > -	struct drm_i915_private *dev_priv = to_i915(dig_port-
> > >base.base.dev);
> > -	u32 live_status_mask = tc_port_live_status_mask(dig_port);
> > -
> > -	/*
> > -	 * The spec says we shouldn't be using the ISR bits for
> > detecting
> > -	 * between TC and TBT. We should use DFLEXDPSP.
> > -	 */
> > -	if (!live_status_mask && !dig_port->tc_legacy_port) {
> > -		icl_tc_phy_disconnect(dig_port);
> > -
> > -		return false;
> > -	}
> > -
> > -	icl_update_tc_port_type(dev_priv, dig_port, live_status_mask);
> > -	if (!icl_tc_phy_connect(dig_port))
> > -		return false;
> > +	if (intel_tc_port_needs_reset(dig_port))
> > +		intel_tc_port_reset_mode(dig_port);
> >  
> > -	return true;
> > +	return tc_port_live_status_mask(dig_port) & BIT(dig_port-
> > >tc_mode);
> >  }
> >  
> >  void intel_tc_port_init(struct intel_digital_port *dig_port, bool
> > is_legacy)
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