drm/i915: Keep the TypeC port mode fixed for detect/AUX transfers

We must keep the TypeC port mode fixed for the duration of the connector
detection and each AUX transfers. Add a new TypeC lock holding it around
these two sequences. For consistency also hold the lock during the port
mode sanitization.

Whenever resetting the port mode (only during the detection for now) the
port's AUX power domain must be disabled already. Flush the async power
domain disabling work to ensure this.

A follow-up patch will make the port mode changing more robust by
postponing the change for active ports.

v2:
- Fix checkpatch issue: missing annotation for tc_lock.

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>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190628143635.22066-15-imre.deak@intel.com

drivers/gpu/drm/i915/display/intel_dp.c

@@ -1192,6 +1192,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
 	struct drm_i915_private *i915 =
 			to_i915(intel_dig_port->base.base.dev);
 	struct intel_uncore *uncore = &i915->uncore;
+	bool is_tc_port = intel_port_is_tc(i915, intel_dig_port->base.port);
 	i915_reg_t ch_ctl, ch_data[5];
 	u32 aux_clock_divider;
 	enum intel_display_power_domain aux_domain =
@@ -1207,6 +1208,9 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
 	for (i = 0; i < ARRAY_SIZE(ch_data); i++)
 		ch_data[i] = intel_dp->aux_ch_data_reg(intel_dp, i);
 
+	if (is_tc_port)
+		intel_tc_port_lock(intel_dig_port);
+
 	aux_wakeref = intel_display_power_get(i915, aux_domain);
 	pps_wakeref = pps_lock(intel_dp);
 
@@ -1359,6 +1363,9 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
 	pps_unlock(intel_dp, pps_wakeref);
 	intel_display_power_put_async(i915, aux_domain, aux_wakeref);
 
+	if (is_tc_port)
+		intel_tc_port_unlock(intel_dig_port);
+
 	return ret;
 }
 

drivers/gpu/drm/i915/display/intel_tc.c

@@ -312,8 +312,11 @@ intel_tc_port_get_target_mode(struct intel_digital_port *dig_port)
 
 static void intel_tc_port_reset_mode(struct intel_digital_port *dig_port)
 {
+	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
 	enum tc_port_mode old_tc_mode = dig_port->tc_mode;
 
+	intel_display_power_flush_work(dev_priv);
+
 	icl_tc_phy_disconnect(dig_port);
 	icl_tc_phy_connect(dig_port);
 
@@ -328,6 +331,8 @@ void intel_tc_port_sanitize(struct intel_digital_port *dig_port)
 	struct intel_encoder *encoder = &dig_port->base;
 	int active_links = 0;
 
+	mutex_lock(&dig_port->tc_lock);
+
 	dig_port->tc_mode = intel_tc_port_get_current_mode(dig_port);
 	if (dig_port->dp.is_mst)
 		active_links = intel_dp_mst_encoder_active_links(dig_port);
@@ -348,6 +353,8 @@ void intel_tc_port_sanitize(struct intel_digital_port *dig_port)
 	DRM_DEBUG_KMS("Port %s: sanitize mode (%s)\n",
 		      dig_port->tc_port_name,
 		      tc_port_mode_name(dig_port->tc_mode));
+
+	mutex_unlock(&dig_port->tc_lock);
 }
 
 static bool intel_tc_port_needs_reset(struct intel_digital_port *dig_port)
@@ -367,10 +374,30 @@ static bool intel_tc_port_needs_reset(struct intel_digital_port *dig_port)
  */
 bool intel_tc_port_connected(struct intel_digital_port *dig_port)
 {
+	bool is_connected;
+
+	mutex_lock(&dig_port->tc_lock);
+
 	if (intel_tc_port_needs_reset(dig_port))
 		intel_tc_port_reset_mode(dig_port);
 
-	return tc_port_live_status_mask(dig_port) & BIT(dig_port->tc_mode);
+	is_connected = tc_port_live_status_mask(dig_port) &
+		       BIT(dig_port->tc_mode);
+
+	mutex_unlock(&dig_port->tc_lock);
+
+	return is_connected;
+}
+
+void intel_tc_port_lock(struct intel_digital_port *dig_port)
+{
+	mutex_lock(&dig_port->tc_lock);
+	/* TODO: reset the TypeC port mode if needed */
+}
+
+void intel_tc_port_unlock(struct intel_digital_port *dig_port)
+{
+	mutex_unlock(&dig_port->tc_lock);
 }
 
 void intel_tc_port_init(struct intel_digital_port *dig_port, bool is_legacy)
@@ -385,5 +412,6 @@ void intel_tc_port_init(struct intel_digital_port *dig_port, bool is_legacy)
 	snprintf(dig_port->tc_port_name, sizeof(dig_port->tc_port_name),
 		 "%c/TC#%d", port_name(port), tc_port + 1);
 
+	mutex_init(&dig_port->tc_lock);
 	dig_port->tc_legacy_port = is_legacy;
 }

drivers/gpu/drm/i915/display/intel_tc.h

@@ -17,6 +17,8 @@ u32 intel_tc_port_get_lane_mask(struct intel_digital_port *dig_port);
 int intel_tc_port_fia_max_lane_count(struct intel_digital_port *dig_port);
 
 void intel_tc_port_sanitize(struct intel_digital_port *dig_port);
+void intel_tc_port_lock(struct intel_digital_port *dig_port);
+void intel_tc_port_unlock(struct intel_digital_port *dig_port);
 
 void intel_tc_port_init(struct intel_digital_port *dig_port, bool is_legacy);
 

drivers/gpu/drm/i915/intel_drv.h

@@ -1224,6 +1224,7 @@ struct intel_digital_port {
 	/* Used for DP and ICL+ TypeC/DP and TypeC/HDMI ports. */
 	enum aux_ch aux_ch;
 	enum intel_display_power_domain ddi_io_power_domain;
+	struct mutex tc_lock;	/* protects the TypeC port mode */
 	bool tc_legacy_port:1;
 	char tc_port_name[8];
 	enum tc_port_mode tc_mode;