3 files changed, 25 insertions, 4 deletions
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index 890fa7ddaa7f..b3c3f7e5851a 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -64,10 +64,19 @@ int serial8250_tx_dma(struct uart_8250_port *p)
 	struct uart_8250_dma		*dma = p->dma;
 	struct circ_buf			*xmit = &p->port.state->xmit;
 	struct dma_async_tx_descriptor	*desc;
+	struct uart_port		*up = &p->port;
 	int ret;
 
-	if (dma->tx_running)
+	if (dma->tx_running) {
+		if (up->x_char) {
+			dmaengine_pause(dma->txchan);
+			uart_xchar_out(up, UART_TX);
+			dmaengine_resume(dma->txchan);
+		}
 		return 0;
+	} else if (up->x_char) {
+		uart_xchar_out(up, UART_TX);
+	}
 
 	if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
 		/* We have been called from __dma_tx_complete() */
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 267026892264..318af6f13605 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1822,9 +1822,7 @@ void serial8250_tx_chars(struct uart_8250_port *up)
 	int count;
 
 	if (port->x_char) {
-		serial_out(up, UART_TX, port->x_char);
-		port->icount.tx++;
-		port->x_char = 0;
+		uart_xchar_out(port, UART_TX);
 		return;
 	}
 	if (uart_tx_stopped(port)) {
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index a1688a341411..6a8963caf954 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -642,6 +642,20 @@ static void uart_flush_buffer(struct tty_struct *tty)
 }
 
 /*
+ * This function performs low-level write of high-priority XON/XOFF
+ * character and accounting for it.
+ *
+ * Requires uart_port to implement .serial_out().
+ */
+void uart_xchar_out(struct uart_port *uport, int offset)
+{
+	serial_port_out(uport, offset, uport->x_char);
+	uport->icount.tx++;
+	uport->x_char = 0;
+}
+EXPORT_SYMBOL_GPL(uart_xchar_out);
+
+/*
  * This function is used to send a high-priority XON/XOFF character to
  * the device
  */