diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index e9eb454c2472..98e68f25a5f3 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -92,10 +92,13 @@ static void mtk8250_dma_rx_complete(void *param)
 	struct dma_tx_state state;
 	int copied, total, cnt;
 	unsigned char *ptr;
+	unsigned long flags;
 
 	if (data->rx_status == DMA_RX_SHUTDOWN)
 		return;
 
+	spin_lock_irqsave(&up->port.lock, flags);
+
 	dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
 	total = dma->rx_size - state.residue;
 	cnt = total;
@@ -119,6 +122,8 @@ static void mtk8250_dma_rx_complete(void *param)
 	tty_flip_buffer_push(tty_port);
 
 	mtk8250_rx_dma(up);
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
 }
 
 static void mtk8250_rx_dma(struct uart_8250_port *up)