diff --git a/sys/dev/drm2/drm_dp_iic_helper.c b/sys/dev/drm2/drm_dp_iic_helper.c
index 71319e3..26f6cbf 100644
--- a/sys/dev/drm2/drm_dp_iic_helper.c
+++ b/sys/dev/drm2/drm_dp_iic_helper.c
@@ -26,6 +26,8 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/kobj.h>
 #include <sys/bus.h>
+#include <sys/param.h>
+#include <sys/stack.h>
 #include <dev/iicbus/iic.h>
 #include "iicbus_if.h"
 #include <dev/iicbus/iiconf.h>
@@ -211,6 +213,7 @@ iic_dp_aux_attach(device_t idev)
 	aux_data->port = device_add_child(idev, "iicbus", -1);
 	if (aux_data->port == NULL)
 		return (ENXIO);
+	DRM_INFO("%s: idev=%p port=%p\n", __func__, idev, aux_data->port);
 	device_quiet(aux_data->port);
 	bus_generic_attach(idev);
 	return (0);
@@ -226,8 +229,13 @@ iic_dp_aux_detach(device_t idev)
 
 	port = aux_data->port;
 	bus_generic_detach(idev);
-	if (port != NULL)
+	if (port != NULL) {
+		struct stack *st;
+		DRM_INFO("%s: idev=%p port=%p\n", __func__, idev, aux_data->port);
+		st = stack_create();
+		stack_print(st);
 		device_delete_child(idev, port);
+	}
 
 	return (0);
 }