diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 952730a..1c4f367 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -502,18 +502,20 @@
 	struct circ_buf *xmit = &sport->port.state->xmit;
 	unsigned long flags;
 
+	spin_lock_irqsave(&sport->port.lock, flags);
+
 	dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
 
+	/* update the stat */
+	xmit->tail = (xmit->tail + sport->tx_bytes) & (UART_XMIT_SIZE - 1);
+	sport->port.icount.tx += sport->tx_bytes;
+
+	dev_dbg(sport->port.dev, "we finish the TX DMA.\n");
+
 	sport->dma_is_txing = 0;
 
-	/* update the stat */
-	spin_lock_irqsave(&sport->port.lock, flags);
-	xmit->tail = (xmit->tail + sport->tx_bytes) & (UART_XMIT_SIZE - 1);
-	sport->port.icount.tx += sport->tx_bytes;
 	spin_unlock_irqrestore(&sport->port.lock, flags);
 
-	dev_dbg(sport->port.dev, "we finish the TX DMA.\n");
-
 	uart_write_wakeup(&sport->port);
 
 	if (waitqueue_active(&sport->dma_wait)) {
@@ -530,11 +532,9 @@
 	struct dma_async_tx_descriptor *desc;
 	struct dma_chan	*chan = sport->dma_chan_tx;
 	struct device *dev = sport->port.dev;
-	enum dma_status status;
 	int ret;
 
-	status = dmaengine_tx_status(chan, (dma_cookie_t)0, NULL);
-	if (DMA_IN_PROGRESS == status)
+	if (sport->dma_is_txing)
 		return;
 
 	sport->tx_bytes = uart_circ_chars_pending(xmit);