8250_core: Fix unwanted TX chars write

On transmit-hold-register empty, serial8250_tx_chars
should be called only if we don't use DMA.
DMA has its own tx cycle.

Signed-off-by: Loic Poulain <loic.poulain@intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 81f909c2101f6145f568fd048b60453533cf943d..0e1bf88584311352767e646faedc2b39183932ce 100644 (file)
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1520,7 +1520,7 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
                        status = serial8250_rx_chars(up, status);
        }
        serial8250_modem_status(up);
-       if (status & UART_LSR_THRE)
+       if (!up->dma && (status & UART_LSR_THRE))
                serial8250_tx_chars(up);
 
        spin_unlock_irqrestore(&port->lock, flags);