tty: serial: men_z135_uart: Wakeup UART after transmitting

Call uart_write_wakeup() after writing the hardware FIFO and updateing the FIFO
pointers.

This fixes high latency and jitter on PPP over Serial links.

Reported-by: Jun Shih <Jun.Shih@pason.com>
Tested-by: Jun Shih <Jun.Shih@pason.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@men.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/men_z135_uart.c b/drivers/tty/serial/men_z135_uart.c
index c9d1854..30e9e60 100644 (file)
--- a/drivers/tty/serial/men_z135_uart.c
+++ b/drivers/tty/serial/men_z135_uart.c
@@ -308,9 +308,6 @@ static void men_z135_handle_tx(struct men_z135_port *uart)
        if (port->x_char)
                goto out;
 
-       if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-               uart_write_wakeup(port);
-
        /* calculate bytes to copy */
        qlen = uart_circ_chars_pending(xmit);
        if (qlen <= 0)
@@ -357,6 +354,9 @@ static void men_z135_handle_tx(struct men_z135_port *uart)
 
        port->icount.tx += n;
 
+       if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+               uart_write_wakeup(port);
+
 irq_en:
        if (!uart_circ_empty(xmit))
                men_z135_reg_set(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_TXCIEN);