From 3473bb1635ef792a49957ac8afa42d7f46f21d70 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Fri, 13 Mar 2015 07:22:43 -0600
Subject: [PATCH] drivers/serial: Report correct number of bytes free in serial
 buffer with FIONWRITE.  From Jussi Kivilinna.

---
 drivers/serial/serial.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index b2719e62a2..d9f161b18a 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -877,7 +877,7 @@ static int uart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
                 }
               else
                 {
-                  count = dev->xmit.size - (dev->xmit.head - dev->xmit.tail) - 1;
+                  count = dev->xmit.size - (dev->xmit.head - dev->xmit.tail);
                 }
 
               irqrestore(state);