drm/i915/icl: Update FIA supported lane count for hpd.

In ICL, Flexible IO Adapter (FIA) muxes data and clocks of USB 3.1,
tbt and display controller. In DP alt mode FIA configure the
number of lanes and will be used apart from DPCD read to calculate max
available lanes for DP enablement.

v2 (from Paulo): Simple rebase.

Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com> (v1).
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
[Paulo: significant rewrite of the patch.]
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180725002813.6938-4-paulo.r.zanoni@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -10705,5 +10705,8 @@ enum skl_power_gate {
 #define PORT_TX_DFLEXDPSP			_MMIO(0x1638A0)
 #define   TC_LIVE_STATE_TBT(tc_port)		(1 << ((tc_port) * 8 + 6))
 #define   TC_LIVE_STATE_TC(tc_port)		(1 << ((tc_port) * 8 + 5))
+#define   DP_LANE_ASSIGNMENT_SHIFT(tc_port)	((tc_port) * 8)
+#define   DP_LANE_ASSIGNMENT_MASK(tc_port)	(0xf << ((tc_port) * 8))
+#define   DP_LANE_ASSIGNMENT(tc_port, x)	((x) << ((tc_port) * 8))
 
 #endif /* _I915_REG_H_ */

drivers/gpu/drm/i915/intel_dp.c

@@ -176,14 +176,45 @@ static int intel_dp_max_common_rate(struct intel_dp *intel_dp)
 	return intel_dp->common_rates[intel_dp->num_common_rates - 1];
 }
 
+static int intel_dp_get_fia_supported_lane_count(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	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 lane_info;
+
+	if (tc_port == PORT_TC_NONE || dig_port->tc_type != TC_PORT_TYPEC)
+		return 4;
+
+	lane_info = (I915_READ(PORT_TX_DFLEXDPSP) &
+		     DP_LANE_ASSIGNMENT_MASK(tc_port)) >>
+		    DP_LANE_ASSIGNMENT_SHIFT(tc_port);
+
+	switch (lane_info) {
+	default:
+		MISSING_CASE(lane_info);
+	case 1:
+	case 2:
+	case 4:
+	case 8:
+		return 1;
+	case 3:
+	case 12:
+		return 2;
+	case 15:
+		return 4;
+	}
+}
+
 /* Theoretical max between source and sink */
 static int intel_dp_max_common_lane_count(struct intel_dp *intel_dp)
 {
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
 	int source_max = intel_dig_port->max_lanes;
 	int sink_max = drm_dp_max_lane_count(intel_dp->dpcd);
+	int fia_max = intel_dp_get_fia_supported_lane_count(intel_dp);
 
-	return min(source_max, sink_max);
+	return min3(source_max, sink_max, fia_max);
 }
 
 int intel_dp_max_lane_count(struct intel_dp *intel_dp)