From b5efb9dd772cac81172755b68ae9b7a93d9d9fa7 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Thu, 8 May 2014 09:01:14 -0600
Subject: [PATCH] Add serial method so that lower half driver can provide RX
 flow control information.  From Jussi Kivilinna

---
 drivers/serial/serial.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index be9219cb16..9754bf391b 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -763,6 +763,17 @@ static ssize_t uart_read(FAR struct file *filep, FAR char *buffer, size_t buflen
         }
     }
 
+#ifdef CONFIG_SERIAL_IFLOWCONTROL
+  if (dev->recv.head == dev->recv.tail)
+    {
+      /* We might leave Rx interrupt disabled if full recv buffer was read
+       * empty. Enable Rx interrupt to make sure that more input is received.
+       */
+
+      uart_enablerxint(dev);
+    }
+#endif
+
   uart_givesem(&dev->recv.sem);
   return recvd;
 }