drm/i915/dp: Do not grab crtc modeset lock in intel_dp_detect()

A crtc modeset lock was added for link retraining but
intel_dp_retrain_link() knows to take the necessary locks since
commit c85d200e ("drm/i915: Move SST DP link retraining into the
->post_hotplug() hook")
v2: Drop AUX power domain reference in the early return path

Fixes: c85d200e ("drm/i915: Move SST DP link retraining into the ->post_hotplug() hook")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180927205735.16651-4-dhinakaran.pandiyan@intel.com

drivers/gpu/drm/i915/intel_dp.c

@@ -5079,8 +5079,16 @@ intel_dp_long_pulse(struct intel_connector *connector,
 	 * Some external monitors do not signal loss of link synchronization
 	 * with an IRQ_HPD, so force a link status check.
 	 */
-	if (!intel_dp_is_edp(intel_dp))
-		intel_dp_retrain_link(encoder, ctx);
+	if (!intel_dp_is_edp(intel_dp)) {
+		int ret;
+
+		ret = intel_dp_retrain_link(encoder, ctx);
+		if (ret) {
+			intel_display_power_put(dev_priv,
+						intel_dp->aux_power_domain);
+			return ret;
+		}
+	}
 
 	/*
 	 * Clearing NACK and defer counts to get their exact values
@@ -5130,19 +5138,8 @@ intel_dp_detect(struct drm_connector *connector,
 		      connector->base.id, connector->name);
 
 	/* If full detect is not performed yet, do a full detect */
-	if (!intel_dp->detect_done) {
-		struct drm_crtc *crtc;
-		int ret;
-
-		crtc = connector->state->crtc;
-		if (crtc) {
-			ret = drm_modeset_lock(&crtc->mutex, ctx);
-			if (ret)
-				return ret;
-		}
-
+	if (!intel_dp->detect_done)
 		status = intel_dp_long_pulse(intel_dp->attached_connector, ctx);
-	}
 
 	intel_dp->detect_done = false;