diff --git a/drivers/staging/emxx_udc/emxx_udc.h b/drivers/staging/emxx_udc/emxx_udc.h
index 789bfb97143c..78c08e15a1f9 100644
--- a/drivers/staging/emxx_udc/emxx_udc.h
+++ b/drivers/staging/emxx_udc/emxx_udc.h
@@ -567,7 +567,7 @@ struct nbu2ss_udc {
 	struct usb_gadget_driver *driver;
 	struct platform_device *pdev;
 	struct device *dev;
-	spinlock_t lock;
+	spinlock_t lock; /* Protects nbu2ss_udc structure fields */
 	struct completion		*pdone;
 
 	enum ep0_state			ep0state;