drm/i915: check connector->encoder before using it.

DP MST will need connectors that aren't connected to specific
encoders, add some checks in advance to avoid oopses.
Reviewed-by: Todd Previte <tprevite@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -2209,6 +2209,7 @@ static void intel_connector_info(struct seq_file *m,
 		seq_printf(m, "\tCEA rev: %d\n",
 			   connector->display_info.cea_rev);
 	}
+	if (intel_encoder) {
 		if (intel_encoder->type == INTEL_OUTPUT_DISPLAYPORT ||
 		    intel_encoder->type == INTEL_OUTPUT_EDP)
 			intel_dp_info(m, intel_connector);
@@ -2216,6 +2217,7 @@ static void intel_connector_info(struct seq_file *m,
 			intel_hdmi_info(m, intel_connector);
 		else if (intel_encoder->type == INTEL_OUTPUT_LVDS)
 			intel_lvds_info(m, intel_connector);
+	}
 
 	seq_printf(m, "\tmodes:\n");
 	list_for_each_entry(mode, &connector->modes, head)

drivers/gpu/drm/i915/i915_irq.c

@@ -1165,6 +1165,8 @@ static void i915_hotplug_work_func(struct work_struct *work)
 	dev_priv->hpd_event_bits = 0;
 	list_for_each_entry(connector, &mode_config->connector_list, head) {
 		intel_connector = to_intel_connector(connector);
+		if (!intel_connector->encoder)
+			continue;
 		intel_encoder = intel_connector->encoder;
 		if (intel_encoder->hpd_pin > HPD_NONE &&
 		    dev_priv->hpd_stats[intel_encoder->hpd_pin].hpd_mark == HPD_MARK_DISABLED &&
@@ -1195,6 +1197,8 @@ static void i915_hotplug_work_func(struct work_struct *work)
 
 	list_for_each_entry(connector, &mode_config->connector_list, head) {
 		intel_connector = to_intel_connector(connector);
+		if (!intel_connector->encoder)
+			continue;
 		intel_encoder = intel_connector->encoder;
 		if (hpd_event_bits & (1 << intel_encoder->hpd_pin)) {
 			if (intel_encoder->hot_plug)

drivers/gpu/drm/i915/intel_display.c

@@ -5003,6 +5003,8 @@ static void intel_connector_check_state(struct intel_connector *connector)
 		     "wrong connector dpms state\n");
 		WARN(connector->base.encoder != &encoder->base,
 		     "active connector not linked to encoder\n");
+
+		if (encoder) {
 			WARN(!encoder->connectors_active,
 			     "encoder->connectors_active not set\n");
 
@@ -5018,6 +5020,7 @@ static void intel_connector_check_state(struct intel_connector *connector)
 			WARN(pipe != to_intel_crtc(crtc)->pipe,
 			     "encoder active on the wrong pipe\n");
 		}
+	}
 }
 
 /* Even simpler default implementation, if there's really no special case to