serial: bfin_uart: Don't switch baud rate untill the transfer buffer is empty.

set_termios may be invoked before the former data transfer is completed.
Block until the tranfer is done.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/tty/serial/bfin_uart.c b/drivers/tty/serial/bfin_uart.c
index 18cf45a29d40..e6a008f4939f 100644
--- a/drivers/tty/serial/bfin_uart.c
+++ b/drivers/tty/serial/bfin_uart.c
@@ -799,6 +799,7 @@ bfin_serial_set_termios(struct uart_port *port, struct ktermios *termios,
         unsigned long flags;
         unsigned int baud, quot;
         unsigned int ier, lcr = 0;
+        unsigned long timeout;
 
         switch (termios->c_cflag & CSIZE) {
         case CS8:
@@ -868,6 +869,14 @@ bfin_serial_set_termios(struct uart_port *port, struct ktermios *termios,
 
         UART_SET_ANOMALY_THRESHOLD(uart, USEC_PER_SEC / baud * 15);
 
+        /* Wait till the transfer buffer is empty */
+        timeout = jiffies + msecs_to_jiffies(10);
+        while (UART_GET_GCTL(uart) & UCEN && !(UART_GET_LSR(uart) & TEMT))
+                if (time_after(jiffies, timeout)) {
+                        dev_warn(port->dev, "timeout waiting for TX buffer empty\n");
+                        break;
+                }
+
         /* Disable UART */
         ier = UART_GET_IER(uart);
         UART_PUT_GCTL(uart, UART_GET_GCTL(uart) & ~UCEN);