drm/i915: Extend hotplug detect retry on TypeC connectors to 5 seconds

On TypeC ports if a sink deasserts/reasserts its HPD signal, generating
a hotplug interrupt without the sink getting unplugged/replugged from
the connector, there can be an up to 3 seconds delay until the AUX
channel gets functional. To avoid detection failures this delay causes
retry the detection for 5 seconds.

I noticed this on ICL/TGL RVPs and a DELL XPS 13 7390 ICL laptop.

References: https://gitlab.freedesktop.org/drm/intel/issues/1067Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200330095425.29113-2-imre.deak@intel.com

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

@@ -4520,7 +4520,10 @@ static enum intel_hotplug_state
 intel_ddi_hotplug(struct intel_encoder *encoder,
 		  struct intel_connector *connector)
 {
+	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
 	struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
+	enum phy phy = intel_port_to_phy(i915, encoder->port);
+	bool is_tc = intel_phy_is_tc(i915, phy);
 	struct drm_modeset_acquire_ctx ctx;
 	enum intel_hotplug_state state;
 	int ret;
@@ -4563,8 +4566,15 @@ intel_ddi_hotplug(struct intel_encoder *encoder,
 	 * valid EDID. To solve this schedule another detection cycle if this
 	 * time around we didn't detect any change in the sink's connection
 	 * status.
+	 *
+	 * Type-c connectors which get their HPD signal deasserted then
+	 * reasserted, without unplugging/replugging the sink from the
+	 * connector, introduce a delay until the AUX channel communication
+	 * becomes functional. Retry the detection for 5 seconds on type-c
+	 * connectors to account for this delay.
 	 */
-	if (state == INTEL_HOTPLUG_UNCHANGED && !connector->hotplug_retries &&
+	if (state == INTEL_HOTPLUG_UNCHANGED &&
+	    connector->hotplug_retries < (is_tc ? 5 : 1) &&
 	    !dig_port->dp.is_mst)
 		state = INTEL_HOTPLUG_RETRY;