serial: imx: terminate the RX DMA when the UART is suspending

When the uart port is suspending, the RX data is useless.
So in this case, we can terminate the RX DMA right now.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Signed-off-by: NFugang Duan <B38611@freescale.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

@@ -436,12 +436,14 @@ static void imx_stop_rx(struct uart_port *port)
 	struct imx_port *sport = (struct imx_port *)port;
 	unsigned long temp;
 
-	/*
-	 * We are maybe in the SMP context, so if the DMA TX thread is running
-	 * on other cpu, we have to wait for it to finish.
-	 */
-	if (sport->dma_is_enabled && sport->dma_is_rxing)
-		return;
+	if (sport->dma_is_enabled && sport->dma_is_rxing) {
+		if (sport->port.suspended) {
+			dmaengine_terminate_all(sport->dma_chan_rx);
+			sport->dma_is_rxing = 0;
+		} else {
+			return;
+		}
+	}
 
 	temp = readl(sport->port.membase + UCR2);
 	writel(temp & ~UCR2_RXEN, sport->port.membase + UCR2);