diff --git a/drivers/staging/greybus/bundle.h b/drivers/staging/greybus/bundle.h
index 18b125e8169b..2dc61ab7495d 100644
--- a/drivers/staging/greybus/bundle.h
+++ b/drivers/staging/greybus/bundle.h
@@ -32,8 +32,6 @@ struct gb_bundle {
 };
 #define to_gb_bundle(d) container_of(d, struct gb_bundle, dev)
 
-#define GB_DEVICE_ID_BAD	0xff
-
 /* Greybus "private" definitions" */
 struct gb_bundle *gb_bundle_create(struct gb_interface *intf, u8 bundle_id,
 				   u8 class);
diff --git a/drivers/staging/greybus/greybus_protocols.h b/drivers/staging/greybus/greybus_protocols.h
index 8370cfead6f2..2e126e671bd6 100644
--- a/drivers/staging/greybus/greybus_protocols.h
+++ b/drivers/staging/greybus/greybus_protocols.h
@@ -54,10 +54,11 @@
 
 /* Fixed IDs for control/svc protocols */
 
-/* Device ID of SVC and AP */
-#define GB_DEVICE_ID_SVC			0
-#define GB_DEVICE_ID_AP				1
-#define GB_DEVICE_ID_MODULES_START		2
+/* SVC switch-port device ids */
+#define GB_SVC_DEVICE_ID_SVC			0
+#define GB_SVC_DEVICE_ID_AP			1
+#define GB_SVC_DEVICE_ID_MIN			2
+#define GB_SVC_DEVICE_ID_MAX			31
 
 #define GB_SVC_CPORT_ID				0
 #define GB_CONTROL_BUNDLE_ID			0
diff --git a/drivers/staging/greybus/interface.c b/drivers/staging/greybus/interface.c
index 48f64fbe9248..7e7bcdafa6e2 100644
--- a/drivers/staging/greybus/interface.c
+++ b/drivers/staging/greybus/interface.c
@@ -10,6 +10,9 @@
 #include "greybus.h"
 
 
+#define GB_INTERFACE_DEVICE_ID_BAD	0xff
+
+
 static int gb_interface_route_create(struct gb_interface *intf)
 {
 	struct gb_svc *svc = intf->hd->svc;
@@ -17,16 +20,10 @@ static int gb_interface_route_create(struct gb_interface *intf)
 	u8 device_id;
 	int ret;
 
-	/*
-	 * Create a device id for the interface:
-	 * - device id 0 (GB_DEVICE_ID_SVC) belongs to the SVC
-	 * - device id 1 (GB_DEVICE_ID_AP) belongs to the AP
-	 *
-	 * XXX Do we need to allocate device ID for SVC or the AP here? And what
-	 * XXX about an AP with multiple interface blocks?
-	 */
+	/* Allocate an interface device id. */
 	ret = ida_simple_get(&svc->device_id_map,
-			     GB_DEVICE_ID_MODULES_START, 0, GFP_KERNEL);
+			     GB_SVC_DEVICE_ID_MIN, GB_SVC_DEVICE_ID_MAX + 1,
+			     GFP_KERNEL);
 	if (ret < 0) {
 		dev_err(&intf->dev, "failed to allocate device id: %d\n", ret);
 		return ret;
@@ -40,8 +37,8 @@ static int gb_interface_route_create(struct gb_interface *intf)
 		goto err_ida_remove;
 	}
 
-	/* Create a two-way route between the AP and the new interface. */
-	ret = gb_svc_route_create(svc, svc->ap_intf_id, GB_DEVICE_ID_AP,
+	/* FIXME: Hard-coded AP device id. */
+	ret = gb_svc_route_create(svc, svc->ap_intf_id, GB_SVC_DEVICE_ID_AP,
 				  intf_id, device_id);
 	if (ret) {
 		dev_err(&intf->dev, "failed to create route: %d\n", ret);
@@ -67,12 +64,12 @@ static void gb_interface_route_destroy(struct gb_interface *intf)
 {
 	struct gb_svc *svc = intf->hd->svc;
 
-	if (intf->device_id == GB_DEVICE_ID_BAD)
+	if (intf->device_id == GB_INTERFACE_DEVICE_ID_BAD)
 		return;
 
 	gb_svc_route_destroy(svc, svc->ap_intf_id, intf->interface_id);
 	ida_simple_remove(&svc->device_id_map, intf->device_id);
-	intf->device_id = GB_DEVICE_ID_BAD;
+	intf->device_id = GB_INTERFACE_DEVICE_ID_BAD;
 }
 
 /*
@@ -257,7 +254,7 @@ struct gb_interface *gb_interface_create(struct gb_host_device *hd,
 	INIT_LIST_HEAD(&intf->manifest_descs);
 
 	/* Invalid device id to start with */
-	intf->device_id = GB_DEVICE_ID_BAD;
+	intf->device_id = GB_INTERFACE_DEVICE_ID_BAD;
 
 	intf->dev.parent = &hd->dev;
 	intf->dev.bus = &greybus_bus_type;
diff --git a/drivers/staging/greybus/interface.h b/drivers/staging/greybus/interface.h
index 5dfaea51eb9f..8b6fcfe90883 100644
--- a/drivers/staging/greybus/interface.h
+++ b/drivers/staging/greybus/interface.h
@@ -21,7 +21,7 @@ struct gb_interface {
 	struct list_head links;	/* gb_host_device->interfaces */
 	struct list_head manifest_descs;
 	u8 interface_id;	/* Physical location within the Endo */
-	u8 device_id;		/* Device id allocated for the interface block by the SVC */
+	u8 device_id;
 
 	/* Information taken from the manifest descriptor */
 	char *vendor_string;