drm/i915: Inspect the right status bits for DP/HDMI hotplug on gen4

The status bits corresponding to the interrupt enable bits are the
"live" hotplug status bits, and reflect the current status of the port
(high for a detected connection, low for a disconnect). The actual bits
corresponding to the interrupt source are elsewhere. The actual event is
then determined by a combination of the interrupt flag and the current
live status (if the interrupt is active, but the current status is not,
then we have detected a disconnect.)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -1558,12 +1558,21 @@
 #define CRT_HOTPLUG_DETECT_VOLTAGE_475MV	(1 << 2)
 
 #define PORT_HOTPLUG_STAT	0x61114
-#define   HDMIB_HOTPLUG_INT_STATUS		(1 << 29)
-#define   DPB_HOTPLUG_INT_STATUS		(1 << 29)
-#define   HDMIC_HOTPLUG_INT_STATUS		(1 << 28)
-#define   DPC_HOTPLUG_INT_STATUS		(1 << 28)
-#define   HDMID_HOTPLUG_INT_STATUS		(1 << 27)
-#define   DPD_HOTPLUG_INT_STATUS		(1 << 27)
+/* HDMI/DP bits are gen4+ */
+#define   DPB_HOTPLUG_LIVE_STATUS               (1 << 29)
+#define   DPC_HOTPLUG_LIVE_STATUS               (1 << 28)
+#define   DPD_HOTPLUG_LIVE_STATUS               (1 << 27)
+#define   DPD_HOTPLUG_INT_STATUS		(3 << 21)
+#define   DPC_HOTPLUG_INT_STATUS		(3 << 19)
+#define   DPB_HOTPLUG_INT_STATUS		(3 << 17)
+/* HDMI bits are shared with the DP bits */
+#define   HDMIB_HOTPLUG_LIVE_STATUS             (1 << 29)
+#define   HDMIC_HOTPLUG_LIVE_STATUS             (1 << 28)
+#define   HDMID_HOTPLUG_LIVE_STATUS             (1 << 27)
+#define   HDMID_HOTPLUG_INT_STATUS		(3 << 21)
+#define   HDMIC_HOTPLUG_INT_STATUS		(3 << 19)
+#define   HDMIB_HOTPLUG_INT_STATUS		(3 << 17)
+/* CRT/TV/SDVO common between gen3+ */
 #define   CRT_HOTPLUG_INT_STATUS		(1 << 11)
 #define   TV_HOTPLUG_INT_STATUS			(1 << 10)
 #define   CRT_HOTPLUG_MONITOR_MASK		(3 << 8)

drivers/gpu/drm/i915/intel_dp.c

@@ -2066,25 +2066,23 @@ g4x_dp_detect(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp->base.base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	uint32_t temp, bit;
+	uint32_t bit;
 
 	switch (intel_dp->output_reg) {
 	case DP_B:
-		bit = DPB_HOTPLUG_INT_STATUS;
+		bit = DPB_HOTPLUG_LIVE_STATUS;
 		break;
 	case DP_C:
-		bit = DPC_HOTPLUG_INT_STATUS;
+		bit = DPC_HOTPLUG_LIVE_STATUS;
 		break;
 	case DP_D:
-		bit = DPD_HOTPLUG_INT_STATUS;
+		bit = DPD_HOTPLUG_LIVE_STATUS;
 		break;
 	default:
 		return connector_status_unknown;
 	}
 
-	temp = I915_READ(PORT_HOTPLUG_STAT);
-
-	if ((temp & bit) == 0)
+	if ((I915_READ(PORT_HOTPLUG_STAT) & bit) == 0)
 		return connector_status_disconnected;
 
 	return intel_dp_detect_dpcd(intel_dp);