diff --git a/include/rdma/ib_cm.h b/include/rdma/ib_cm.h
index 12243e8..a627c86 100644
--- a/include/rdma/ib_cm.h
+++ b/include/rdma/ib_cm.h
@@ -477,12 +477,15 @@
 		   const void *private_data,
 		   u8 private_data_len);
 
+#define IB_CM_MRA_FLAG_DELAY 0x80  /* Send MRA only after a duplicate msg */
+
 /**
  * ib_send_cm_mra - Sends a message receipt acknowledgement to a connection
  *   message.
  * @cm_id: Connection identifier associated with the connection message.
- * @service_timeout: The maximum time required for the sender to reply to
- *   to the connection message.
+ * @service_timeout: The lower 5-bits specify the maximum time required for
+ *   the sender to reply to to the connection message.  The upper 3-bits
+ *   specify additional control flags.
  * @private_data: Optional user-defined private data sent with the
  *   message receipt acknowledgement.
  * @private_data_len: Size of the private data buffer, in bytes.