drm/i915: propagate errors from intel_dp_init_connector

In case we detect a "ghost eDP", intel_edp_init_connector frees both
the connector and encoder and then returns. On Haswell, intel_ddi_init
then tries to use the freed encoder on the HDMI initialization path
since the following commit:

commit 21a8e6a4
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Apr 10 23:28:35 2013 +0200
    drm/i915: don't setup hdmi for port D edp in ddi_init

So now on intel_ddi_init we check for the "ghost eDP" case and return
without trying to initialize HDMI. This way we won't try to read the
freed "intel_encoder" struct in the next "if" statement.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Zoltan Nyul <zoltan.nyul@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -1356,7 +1356,8 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
 	intel_encoder->cloneable = false;
 	intel_encoder->hot_plug = intel_ddi_hot_plug;
 
-	intel_dp_init_connector(intel_dig_port, dp_connector);
+	if (!intel_dp_init_connector(intel_dig_port, dp_connector))
+		return;
 
 	if (intel_encoder->type != INTEL_OUTPUT_EDP) {
 		hdmi_connector = kzalloc(sizeof(struct intel_connector),

drivers/gpu/drm/i915/intel_dp.c

@@ -3035,7 +3035,7 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
 	return true;
 }
 
-void
+bool
 intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 			struct intel_connector *intel_connector)
 {
@@ -3147,7 +3147,7 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 	intel_dp_i2c_init(intel_dp, intel_connector, name);
 
 	if (!intel_edp_init_connector(intel_dp, intel_connector))
-		return;
+		return false;
 
 	intel_dp_add_properties(intel_dp, connector);
 
@@ -3159,6 +3159,8 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 		u32 temp = I915_READ(PEG_BAND_GAP_DATA);
 		I915_WRITE(PEG_BAND_GAP_DATA, (temp & ~0xf) | 0xd);
 	}
+
+	return true;
 }
 
 void

drivers/gpu/drm/i915/intel_drv.h

@@ -586,7 +586,7 @@ extern void intel_lvds_init(struct drm_device *dev);
 extern bool intel_is_dual_link_lvds(struct drm_device *dev);
 extern void intel_dp_init(struct drm_device *dev, int output_reg,
 			  enum port port);
-extern void intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
+extern bool intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 				    struct intel_connector *intel_connector);
 extern void intel_dp_init_link_config(struct intel_dp *intel_dp);
 extern void intel_dp_start_link_train(struct intel_dp *intel_dp);