1 files changed, 21 insertions, 9 deletions

diff --git a/drivers/serial/bfin_sport_uart.c b/drivers/serial/bfin_sport_uart.c
index b9938acb0309..0b459cf1b2eb 100644
--- a/drivers/serial/bfin_sport_uart.c
+++ b/drivers/serial/bfin_sport_uart.c
@@ -54,7 +54,7 @@ struct sport_uart_port {
 #endif
 };
 
-static void sport_uart_tx_chars(struct sport_uart_port *up);
+static int sport_uart_tx_chars(struct sport_uart_port *up);
 static void sport_stop_tx(struct uart_port *port);
 
 static inline void tx_one_byte(struct sport_uart_port *up, unsigned int value)
@@ -307,18 +307,24 @@ static int sport_startup(struct uart_port *port)
         return ret;
 }
 
-static void sport_uart_tx_chars(struct sport_uart_port *up)
+/*
+ * sport_uart_tx_chars
+ *
+ * ret 1 means need to enable sport.
+ * ret 0 means do nothing.
+ */
+static int sport_uart_tx_chars(struct sport_uart_port *up)
 {
         struct circ_buf *xmit = &up->port.state->xmit;
 
         if (SPORT_GET_STAT(up) & TXF)
-                return;
+                return 0;
 
         if (up->port.x_char) {
                 tx_one_byte(up, up->port.x_char);
                 up->port.icount.tx++;
                 up->port.x_char = 0;
-                return;
+                return 1;
         }
 
         if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
@@ -329,7 +335,7 @@ static void sport_uart_tx_chars(struct sport_uart_port *up)
                  */
                 if (SPORT_GET_STAT(up) & TXHRE)
                         sport_stop_tx(&up->port);
-                return;
+                return 0;
         }
 
         while(!(SPORT_GET_STAT(up) & TXF) && !uart_circ_empty(xmit)) {
@@ -340,6 +346,8 @@ static void sport_uart_tx_chars(struct sport_uart_port *up)
 
         if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
                 uart_write_wakeup(&up->port);
+
+        return 1;
 }
 
 static unsigned int sport_tx_empty(struct uart_port *port)
@@ -361,6 +369,9 @@ static void sport_stop_tx(struct uart_port *port)
 
         pr_debug("%s enter\n", __func__);
 
+        if (!(SPORT_GET_TCR1(up) & TSPEN))
+                return;
+
         /* Although the hold register is empty, last byte is still in shift
          * register and not sent out yet. So, put a dummy data into TX FIFO.
          * Then, sport tx stops when last byte is shift out and the dummy
@@ -383,11 +394,12 @@ static void sport_start_tx(struct uart_port *port)
         pr_debug("%s enter\n", __func__);
 
         /* Write data into SPORT FIFO before enable SPROT to transmit */
-        sport_uart_tx_chars(up);
+        if (sport_uart_tx_chars(up)) {
+                /* Enable transmit, then an interrupt will generated */
+                SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) | TSPEN));
+                SSYNC();
+        }
 
-        /* Enable transmit, then an interrupt will generated */
-        SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) | TSPEN));
-        SSYNC();
         pr_debug("%s exit\n", __func__);
 }