[PATCH 1/7] serial: imx: only set DMA rx-ing when DMA starts

[Romain Perier]

From: Nandor Han <nandor....@ge.com>

Avoid the situation when `dma_is_rxing` could incorrectly signal that
DMA RX channel is receiving data in case DMA preparation or sg mapping
fails.

Signed-off-by: Nandor Han <nandor....@ge.com>
Signed-off-by: Romain Perier <romain.per...@collabora.com>
---
 drivers/tty/serial/imx.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 5437b34..1d35293 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -725,11 +725,11 @@ static irqreturn_t imx_rxint(int irq, void *dev_id)
        return IRQ_HANDLED;
 }
 
-static void imx_disable_rx_int(struct imx_port *sport)
+static void imx_disable_rx_int(struct imx_port *sport, bool is_rxing)
 {
        unsigned long temp;
 
-       sport->dma_is_rxing = 1;
+       sport->dma_is_rxing = is_rxing;
 
        /* disable the receiver ready and aging timer interrupts */
        temp = readl(sport->port.membase + UCR1);
@@ -762,7 +762,7 @@ static void imx_dma_rxint(struct imx_port *sport)
        temp = readl(sport->port.membase + USR2);
        if ((temp & USR2_RDR) && !sport->dma_is_rxing) {
 
-               imx_disable_rx_int(sport);
+               imx_disable_rx_int(sport, false);
 
                /* tell the DMA to receive the data. */
                start_rx_dma(sport);
@@ -1083,6 +1083,7 @@ static int start_rx_dma(struct imx_port *sport)
        desc->callback_param = sport;
 
        dev_dbg(dev, "RX: prepare for the DMA.\n");
+       sport->dma_is_rxing = 1;
        sport->rx_cookie = dmaengine_submit(desc);
        dma_async_issue_pending(chan);
        return 0;
@@ -1362,7 +1363,7 @@ static int imx_startup(struct uart_port *port)
                spin_unlock(&tty->files_lock);
 
                if (readcnt > 0) {
-                       imx_disable_rx_int(sport);
+                       imx_disable_rx_int(sport, true);
                        start_rx_dma(sport);
                }
        }
-- 
1.8.3.1