diff --git a/drivers/usb/pd/policy_engine.c b/drivers/usb/pd/policy_engine.c
index 8b82d3960752..b4d7c7d8bddf 100644
--- a/drivers/usb/pd/policy_engine.c
+++ b/drivers/usb/pd/policy_engine.c
@@ -942,6 +942,13 @@ int usbpd_register_svid(struct usbpd *pd, struct usbpd_svid_handler *hdlr)
 		return -EINVAL;
 	}
 
+	/* require connect/disconnect callbacks be implemented */
+	if (!hdlr->connect || !hdlr->disconnect) {
+		usbpd_err(&pd->dev, "SVID 0x%04x connect/disconnect must be non-NULL\n",
+				hdlr->svid);
+		return -EINVAL;
+	}
+
 	usbpd_dbg(&pd->dev, "registered handler for SVID 0x%04x\n", hdlr->svid);
 
 	list_add_tail(&hdlr->entry, &pd->svid_handlers);
@@ -952,8 +959,8 @@ int usbpd_register_svid(struct usbpd *pd, struct usbpd_svid_handler *hdlr)
 
 		for (i = 0; i < pd->num_svids; i++) {
 			if (pd->discovered_svids[i] == hdlr->svid) {
-				if (hdlr->connect)
-					hdlr->connect(hdlr);
+				hdlr->connect(hdlr);
+				hdlr->discovered = true;
 				break;
 			}
 		}
@@ -1165,8 +1172,10 @@ static void handle_vdm_rx(struct usbpd *pd, struct rx_msg *rx_msg)
 				svid = pd->discovered_svids[i];
 				if (svid) {
 					handler = find_svid_handler(pd, svid);
-					if (handler && handler->connect)
+					if (handler) {
 						handler->connect(handler);
+						handler->discovered = true;
+					}
 				}
 			}
 
@@ -1271,10 +1280,14 @@ static void reset_vdm_state(struct usbpd *pd)
 {
 	struct usbpd_svid_handler *handler;
 
-	pd->vdm_state = VDM_NONE;
-	list_for_each_entry(handler, &pd->svid_handlers, entry)
-		if (handler->disconnect)
+	list_for_each_entry(handler, &pd->svid_handlers, entry) {
+		if (handler->discovered) {
 			handler->disconnect(handler);
+			handler->discovered = false;
+		}
+	}
+
+	pd->vdm_state = VDM_NONE;
 	kfree(pd->vdm_tx_retry);
 	pd->vdm_tx_retry = NULL;
 	kfree(pd->discovered_svids);
diff --git a/include/linux/usb/usbpd.h b/include/linux/usb/usbpd.h
index c2c1025feb8e..3566a7a974d1 100644
--- a/include/linux/usb/usbpd.h
+++ b/include/linux/usb/usbpd.h
@@ -42,6 +42,7 @@ enum usbpd_svdm_cmd_type {
 struct usbpd_svid_handler {
 	u16 svid;
 
+	/* Notified when VDM session established/reset; must be implemented */
 	void (*connect)(struct usbpd_svid_handler *hdlr);
 	void (*disconnect)(struct usbpd_svid_handler *hdlr);
 
@@ -54,7 +55,9 @@ struct usbpd_svid_handler {
 			enum usbpd_svdm_cmd_type cmd_type, const u32 *vdos,
 			int num_vdos);
 
+	/* client should leave these blank; private members used by PD driver */
 	struct list_head entry;
+	bool discovered;
 };
 
 enum plug_orientation {