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

["Souza, Jose" <jose.souza@intel.com>]

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?

>  
> -	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?

>  }
>  
> -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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