Patch "[PATCH 131/135] drm/i915: Check VBT for port presence in addition to" has been added to the 4.4-stable tree

@@ -3313,6 +3313,9 @@ static inline bool intel_gmbus_is_forced
 }
 extern void intel_i2c_reset(struct drm_device *dev);
 
+/* intel_bios.c */
+bool intel_bios_is_port_present(struct drm_i915_private *dev_priv, enum port port);
+
 /* intel_opregion.c */
 #ifdef CONFIG_ACPI
 extern int intel_opregion_setup(struct drm_device *dev);

@@ -1351,3 +1351,42 @@ intel_parse_bios(struct drm_device *dev)
 
 	return 0;
 }
+
+/**
+ * intel_bios_is_port_present - is the specified digital port present
+ * @dev_priv:	i915 device instance
+ * @port:	port to check
+ *
+ * Return true if the device in %port is present.
+ */
+bool intel_bios_is_port_present(struct drm_i915_private *dev_priv, enum port port)
+{
+	static const struct {
+		u16 dp, hdmi;
+	} port_mapping[] = {
+		[PORT_B] = { DVO_PORT_DPB, DVO_PORT_HDMIB, },
+		[PORT_C] = { DVO_PORT_DPC, DVO_PORT_HDMIC, },
+		[PORT_D] = { DVO_PORT_DPD, DVO_PORT_HDMID, },
+		[PORT_E] = { DVO_PORT_DPE, DVO_PORT_HDMIE, },
+	};
+	int i;
+
+	/* FIXME maybe deal with port A as well? */
+	if (WARN_ON(port == PORT_A) || port >= ARRAY_SIZE(port_mapping))
+		return false;
+
+	if (!dev_priv->vbt.child_dev_num)
+		return false;
+
+	for (i = 0; i < dev_priv->vbt.child_dev_num; i++) {
+		const union child_device_config *p_child =
+			&dev_priv->vbt.child_dev[i];
+		if ((p_child->common.dvo_port == port_mapping[port].dp ||
+		     p_child->common.dvo_port == port_mapping[port].hdmi) &&
+		    (p_child->common.device_type & (DEVICE_TYPE_TMDS_DVI_SIGNALING |
+						    DEVICE_TYPE_DISPLAYPORT_OUTPUT)))
+			return true;
+	}
+
+	return false;
+}

@@ -14160,7 +14160,7 @@ static void intel_setup_outputs(struct d
 		if (I915_READ(PCH_DP_D) & DP_DETECTED)
 			intel_dp_init(dev, PCH_DP_D, PORT_D);
 	} else if (IS_VALLEYVIEW(dev)) {
-		bool has_edp;
+		bool has_edp, has_port;
 
 		/*
 		 * The DP_DETECTED bit is the latched state of the DDC

@@ -14170,25 +14170,37 @@ static void intel_setup_outputs(struct d
 		 * Thus we can't rely on the DP_DETECTED bit alone to detect
 		 * eDP ports. Consult the VBT as well as DP_DETECTED to
 		 * detect eDP ports.
+		 *
+		 * Sadly the straps seem to be missing sometimes even for HDMI
+		 * ports (eg. on Voyo V3 - CHT x7-Z8700), so check both strap
+		 * and VBT for the presence of the port. Additionally we can't
+		 * trust the port type the VBT declares as we've seen at least
+		 * HDMI ports that the VBT claim are DP or eDP.
 		 */
 		has_edp = intel_dp_is_edp(dev, PORT_B);
-		if (I915_READ(VLV_DP_B) & DP_DETECTED || has_edp)
+		has_port = intel_bios_is_port_present(dev_priv, PORT_B);
+		if (I915_READ(VLV_DP_B) & DP_DETECTED || has_port)
 			has_edp &= intel_dp_init(dev, VLV_DP_B, PORT_B);
-		if (I915_READ(VLV_HDMIB) & SDVO_DETECTED && !has_edp)
+		if ((I915_READ(VLV_HDMIB) & SDVO_DETECTED || has_port) && !has_edp)
 			intel_hdmi_init(dev, VLV_HDMIB, PORT_B);
 
 		has_edp = intel_dp_is_edp(dev, PORT_C);
-		if (I915_READ(VLV_DP_C) & DP_DETECTED || has_edp)
+		has_port = intel_bios_is_port_present(dev_priv, PORT_C);
+		if (I915_READ(VLV_DP_C) & DP_DETECTED || has_port)
 			has_edp &= intel_dp_init(dev, VLV_DP_C, PORT_C);
-		if (I915_READ(VLV_HDMIC) & SDVO_DETECTED && !has_edp)
+		if ((I915_READ(VLV_HDMIC) & SDVO_DETECTED || has_port) && !has_edp)
 			intel_hdmi_init(dev, VLV_HDMIC, PORT_C);
 
 		if (IS_CHERRYVIEW(dev)) {
-			/* eDP not supported on port D, so don't check VBT */
-			if (I915_READ(CHV_HDMID) & SDVO_DETECTED)
-				intel_hdmi_init(dev, CHV_HDMID, PORT_D);
-			if (I915_READ(CHV_DP_D) & DP_DETECTED)
+			/*
+			 * eDP not supported on port D,
+			 * so no need to worry about it
+			 */
+			has_port = intel_bios_is_port_present(dev_priv, PORT_D);
+			if (I915_READ(CHV_DP_D) & DP_DETECTED || has_port)
 				intel_dp_init(dev, CHV_DP_D, PORT_D);
+			if (I915_READ(CHV_HDMID) & SDVO_DETECTED || has_port)
+				intel_hdmi_init(dev, CHV_HDMID, PORT_D);
 		}
 
 		intel_dsi_init(dev);

@@ -2030,6 +2030,9 @@ void intel_hdmi_init_connector(struct in
 	enum port port = intel_dig_port->port;
 	uint8_t alternate_ddc_pin;
 
+	DRM_DEBUG_KMS("Adding HDMI connector on port %c\n",
+		      port_name(port));
+
 	drm_connector_init(dev, connector, &intel_hdmi_connector_funcs,
 			   DRM_MODE_CONNECTOR_HDMIA);
 	drm_connector_helper_add(connector, &intel_hdmi_connector_helper_funcs);