diff --git a/configs/metro-m4/README.txt b/configs/metro-m4/README.txt
index a9e81cd70fe7..fa314231edc1 100644
--- a/configs/metro-m4/README.txt
+++ b/configs/metro-m4/README.txt
@@ -30,6 +30,9 @@ STATUS
     configuration options still need to be verified.  Unverified SERCOM
     USART, SPI, I2C, Port configuration, and DMA support have been added.
     I still have no hardware in hand to test.
+  2018-07-20:  Brought in the USB driver from the SAML21.  It is the same
+    USB IP with only small differences.  There a a few, small open issues
+    still to be resolved.
 
 Serial Console
 ==============
diff --git a/drivers/usbhost/usbhost_max3421e.c b/drivers/usbhost/usbhost_max3421e.c
index c4f19efbdbbb..160185a2069a 100644
--- a/drivers/usbhost/usbhost_max3421e.c
+++ b/drivers/usbhost/usbhost_max3421e.c
@@ -3065,7 +3065,7 @@ static void max3421e_irqwork(FAR void *arg)
 
   /* Get exclusive access to the SPI bus */
 
-  max3421e_unlock(priv);
+  max3421e_lock(priv);
 
   /* Loop while there are pending interrupts to process.  This loop may save a
    * little interrupt handling overhead.