drm/i915: Respect alternate_ddc_pin for all DDI ports

The VBT provides the platform a way to mix and match the DDI ports vs.
GMBUS pins. Currently we only trust the VBT for DDI E, which I suppose
has no standard GMBUS pin assignment. However, there are machines out
there that use a non-standard mapping for the other ports as well.
Let's start trusting the VBT on this one for all ports on DDI platforms.

I've structured the code such that other platforms could easily start
using this as well, by simply filling in the ddi_port_info. IIRC there
may be CHV system that might actually need this.

v2: Include a commit message, include a debug message during init

Cc: stable@vger.kernel.org
Cc: Maarten Maathuis <madman2003@gmail.com>
Tested-by: Maarten Maathuis <madman2003@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97877
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1476208368-5710-3-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Jim Bride <jim.bride@linux.intel.com>

drivers/gpu/drm/i915/intel_hdmi.c

@@ -1800,6 +1800,50 @@ intel_hdmi_add_properties(struct intel_hdmi *intel_hdmi, struct drm_connector *c
 	intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
 }
 
+static u8 intel_hdmi_ddc_pin(struct drm_i915_private *dev_priv,
+			     enum port port)
+{
+	const struct ddi_vbt_port_info *info =
+		&dev_priv->vbt.ddi_port_info[port];
+	u8 ddc_pin;
+
+	if (info->alternate_ddc_pin) {
+		DRM_DEBUG_KMS("Using DDC pin 0x%x for port %c (VBT)\n",
+			      info->alternate_ddc_pin, port_name(port));
+		return info->alternate_ddc_pin;
+	}
+
+	switch (port) {
+	case PORT_B:
+		if (IS_BROXTON(dev_priv))
+			ddc_pin = GMBUS_PIN_1_BXT;
+		else
+			ddc_pin = GMBUS_PIN_DPB;
+		break;
+	case PORT_C:
+		if (IS_BROXTON(dev_priv))
+			ddc_pin = GMBUS_PIN_2_BXT;
+		else
+			ddc_pin = GMBUS_PIN_DPC;
+		break;
+	case PORT_D:
+		if (IS_CHERRYVIEW(dev_priv))
+			ddc_pin = GMBUS_PIN_DPD_CHV;
+		else
+			ddc_pin = GMBUS_PIN_DPD;
+		break;
+	default:
+		MISSING_CASE(port);
+		ddc_pin = GMBUS_PIN_DPB;
+		break;
+	}
+
+	DRM_DEBUG_KMS("Using DDC pin 0x%x for port %c (platform default)\n",
+		      ddc_pin, port_name(port));
+
+	return ddc_pin;
+}
+
 void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
 			       struct intel_connector *intel_connector)
 {
@@ -1809,7 +1853,6 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
 	struct drm_device *dev = intel_encoder->base.dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	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));
@@ -1827,12 +1870,10 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
 	connector->doublescan_allowed = 0;
 	connector->stereo_allowed = 1;
 
+	intel_hdmi->ddc_bus = intel_hdmi_ddc_pin(dev_priv, port);
+
 	switch (port) {
 	case PORT_B:
-		if (IS_BROXTON(dev_priv))
-			intel_hdmi->ddc_bus = GMBUS_PIN_1_BXT;
-		else
-			intel_hdmi->ddc_bus = GMBUS_PIN_DPB;
 		/*
 		 * On BXT A0/A1, sw needs to activate DDIA HPD logic and
 		 * interrupts to check the external panel connection.
@@ -1843,46 +1884,17 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
 			intel_encoder->hpd_pin = HPD_PORT_B;
 		break;
 	case PORT_C:
-		if (IS_BROXTON(dev_priv))
-			intel_hdmi->ddc_bus = GMBUS_PIN_2_BXT;
-		else
-			intel_hdmi->ddc_bus = GMBUS_PIN_DPC;
 		intel_encoder->hpd_pin = HPD_PORT_C;
 		break;
 	case PORT_D:
-		if (WARN_ON(IS_BROXTON(dev_priv)))
-			intel_hdmi->ddc_bus = GMBUS_PIN_DISABLED;
-		else if (IS_CHERRYVIEW(dev_priv))
-			intel_hdmi->ddc_bus = GMBUS_PIN_DPD_CHV;
-		else
-			intel_hdmi->ddc_bus = GMBUS_PIN_DPD;
 		intel_encoder->hpd_pin = HPD_PORT_D;
 		break;
 	case PORT_E:
-		/* On SKL PORT E doesn't have seperate GMBUS pin
-		 *  We rely on VBT to set a proper alternate GMBUS pin. */
-		alternate_ddc_pin =
-			dev_priv->vbt.ddi_port_info[PORT_E].alternate_ddc_pin;
-		switch (alternate_ddc_pin) {
-		case DDC_PIN_B:
-			intel_hdmi->ddc_bus = GMBUS_PIN_DPB;
-			break;
-		case DDC_PIN_C:
-			intel_hdmi->ddc_bus = GMBUS_PIN_DPC;
-			break;
-		case DDC_PIN_D:
-			intel_hdmi->ddc_bus = GMBUS_PIN_DPD;
-			break;
-		default:
-			MISSING_CASE(alternate_ddc_pin);
-		}
 		intel_encoder->hpd_pin = HPD_PORT_E;
 		break;
-	case PORT_A:
-		intel_encoder->hpd_pin = HPD_PORT_A;
-		/* Internal port only for eDP. */
 	default:
-		BUG();
+		MISSING_CASE(port);
+		return;
 	}
 
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {