drm/i915: Only ignore eDP ports that are connected

If the VBT says that a certain port should be eDP (and hence fused off
from HDMI), but in reality it isn't, we need to try and acquire the HDMI
connection instead. So only trust the VBT edp setting if we can connect
to an eDP device on that port.

Fixes: d2182a6608 (drm/i915: Don't register HDMI connectors for eDP ports on VLV/CHV)
References: https://bugs.freedesktop.org/show_bug.cgi?id=96288
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Phidias Chiang <phidias.chiang@canonical.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1464766070-31623-1-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index fd140c39..08b173c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14702,6 +14702,8 @@
 		if (I915_READ(PCH_DP_D) & DP_DETECTED)
 			intel_dp_init(dev, PCH_DP_D, PORT_D);
 	} else if (IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev)) {
+		bool has_edp;
+
 		/*
 		 * The DP_DETECTED bit is the latched state of the DDC
 		 * SDA pin at boot. However since eDP doesn't require DDC
@@ -14711,19 +14713,17 @@
 		 * eDP ports. Consult the VBT as well as DP_DETECTED to
 		 * detect eDP ports.
 		 */
-		if (I915_READ(VLV_HDMIB) & SDVO_DETECTED &&
-		    !intel_dp_is_edp(dev, PORT_B))
+		has_edp = intel_dp_is_edp(dev, PORT_B);
+		if (I915_READ(VLV_DP_B) & DP_DETECTED || has_edp)
+			has_edp &= intel_dp_init(dev, VLV_DP_B, PORT_B);
+		if (I915_READ(VLV_HDMIB) & SDVO_DETECTED && !has_edp)
 			intel_hdmi_init(dev, VLV_HDMIB, PORT_B);
-		if (I915_READ(VLV_DP_B) & DP_DETECTED ||
-		    intel_dp_is_edp(dev, PORT_B))
-			intel_dp_init(dev, VLV_DP_B, PORT_B);
 
-		if (I915_READ(VLV_HDMIC) & SDVO_DETECTED &&
-		    !intel_dp_is_edp(dev, PORT_C))
+		has_edp = intel_dp_is_edp(dev, PORT_C);
+		if (I915_READ(VLV_DP_C) & DP_DETECTED || has_edp)
+			has_edp &= intel_dp_init(dev, VLV_DP_C, PORT_C);
+		if (I915_READ(VLV_HDMIC) & SDVO_DETECTED && !has_edp)
 			intel_hdmi_init(dev, VLV_HDMIC, PORT_C);
-		if (I915_READ(VLV_DP_C) & DP_DETECTED ||
-		    intel_dp_is_edp(dev, PORT_C))
-			intel_dp_init(dev, VLV_DP_C, PORT_C);
 
 		if (IS_CHERRYVIEW(dev)) {
 			/* eDP not supported on port D, so don't check VBT */