drm/i915: Splitting intel_dp_detect

intel_dp_detect() is called for not just detection but
during modes enumeration as well. Repeating the whole
sequence during each of these calls is wasteful and
time consuming.
This patch moves probing for panel, DPCD read etc done in
intel_dp_detect() to a new function intel_dp_long_pulse().
Note that the behavior of intel_dp_detect() is changed to
report connected or disconnected depending on whether the
EDID is available or not.
This change will be required by further patches in the series
to avoid performing duplicated DPCD operations on hotplug.

v2: Moved a hunk to next patch of the series.
    Moved intel_dp_unset_edid to out. (Ander)

v3: Rephrased commit message and intel_dp_unset_dp() is called
    within intel_dp_set_dp() to free the previous EDID. (Ander)

v4: Added overriding of status to disconnected for MST. (Ander)
Tested-by: Nathan D Ciobanu <nathan.d.ciobanu@intel.com>
Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Shubhangi Shrivastava <shubhangi.shrivastava@intel.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
[anderco: fix parenthesis alignment]
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459341326-13142-1-git-send-email-shubhangi.shrivastava@intel.com

drivers/gpu/drm/i915/intel_dp.c

@@ -129,6 +129,7 @@ static void edp_panel_vdd_off(struct intel_dp *intel_dp, bool sync);
 static void vlv_init_panel_power_sequencer(struct intel_dp *intel_dp);
 static void vlv_steal_power_sequencer(struct drm_device *dev,
 				      enum pipe pipe);
+static void intel_dp_unset_edid(struct intel_dp *intel_dp);
 
 static unsigned int intel_dp_unused_lane_mask(int lane_count)
 {
@@ -4513,6 +4514,7 @@ intel_dp_set_edid(struct intel_dp *intel_dp)
 	struct intel_connector *intel_connector = intel_dp->attached_connector;
 	struct edid *edid;
 
+	intel_dp_unset_edid(intel_dp);
 	edid = intel_dp_get_edid(intel_dp);
 	intel_connector->detect_edid = edid;
 
@@ -4533,9 +4535,10 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
 	intel_dp->has_audio = false;
 }
 
-static enum drm_connector_status
-intel_dp_detect(struct drm_connector *connector, bool force)
+static void
+intel_dp_long_pulse(struct intel_connector *intel_connector)
 {
+	struct drm_connector *connector = &intel_connector->base;
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
 	struct intel_encoder *intel_encoder = &intel_dig_port->base;
@@ -4545,17 +4548,6 @@ intel_dp_detect(struct drm_connector *connector, bool force)
 	bool ret;
 	u8 sink_irq_vector;
 
-	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
-		      connector->base.id, connector->name);
-	intel_dp_unset_edid(intel_dp);
-
-	if (intel_dp->is_mst) {
-		/* MST devices are disconnected from a monitor POV */
-		if (intel_encoder->type != INTEL_OUTPUT_EDP)
-			intel_encoder->type = INTEL_OUTPUT_DISPLAYPORT;
-		return connector_status_disconnected;
-	}
-
 	power_domain = intel_display_port_aux_power_domain(intel_encoder);
 	intel_display_power_get(to_i915(dev), power_domain);
 
@@ -4576,14 +4568,18 @@ intel_dp_detect(struct drm_connector *connector, bool force)
 		goto out;
 	}
 
+	if (intel_encoder->type != INTEL_OUTPUT_EDP)
+		intel_encoder->type = INTEL_OUTPUT_DISPLAYPORT;
+
 	intel_dp_probe_oui(intel_dp);
 
 	ret = intel_dp_probe_mst(intel_dp);
 	if (ret) {
-		/* if we are in MST mode then this connector
-		   won't appear connected or have anything with EDID on it */
-		if (intel_encoder->type != INTEL_OUTPUT_EDP)
-			intel_encoder->type = INTEL_OUTPUT_DISPLAYPORT;
+		/*
+		 * If we are in MST mode then this connector
+		 * won't appear connected or have anything
+		 * with EDID on it
+		 */
 		status = connector_status_disconnected;
 		goto out;
 	}
@@ -4598,8 +4594,6 @@ intel_dp_detect(struct drm_connector *connector, bool force)
 
 	intel_dp_set_edid(intel_dp);
 
-	if (intel_encoder->type != INTEL_OUTPUT_EDP)
-		intel_encoder->type = INTEL_OUTPUT_DISPLAYPORT;
 	status = connector_status_connected;
 
 	/* Try to read the source of the interrupt */
@@ -4617,8 +4611,37 @@ intel_dp_detect(struct drm_connector *connector, bool force)
 	}
 
 out:
+	if (status != connector_status_connected)
+		intel_dp_unset_edid(intel_dp);
 	intel_display_power_put(to_i915(dev), power_domain);
-	return status;
+	return;
+}
+
+static enum drm_connector_status
+intel_dp_detect(struct drm_connector *connector, bool force)
+{
+	struct intel_dp *intel_dp = intel_attached_dp(connector);
+	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+	struct intel_encoder *intel_encoder = &intel_dig_port->base;
+	struct intel_connector *intel_connector = to_intel_connector(connector);
+
+	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
+		      connector->base.id, connector->name);
+
+	if (intel_dp->is_mst) {
+		/* MST devices are disconnected from a monitor POV */
+		intel_dp_unset_edid(intel_dp);
+		if (intel_encoder->type != INTEL_OUTPUT_EDP)
+			intel_encoder->type = INTEL_OUTPUT_DISPLAYPORT;
+		return connector_status_disconnected;
+	}
+
+	intel_dp_long_pulse(intel_dp->attached_connector);
+
+	if (intel_connector->detect_edid)
+		return connector_status_connected;
+	else
+		return connector_status_disconnected;
 }
 
 static void