serial: 8250_omap: pause DMA only if DMA transfer in progress

It is possible that DMA transfer is already complete but, completion
handler is yet to be called, when dmaengine_pause() is called in case of
error condition(like break/rx timeout). This leads to dmaengine_pause()
API to return EINVAL (as descriptor is already NULL) causing
rx_dma_broken flag to be set and effectively disabling RX DMA.
Fix this by calling dmaengine_pause() only when transfer is in progress.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 61ad6c3b20a02b82e6aa95b46fc6d467edc86334..4ad1934ef6ed2f9e45eb078f6ec6b03fbab2ce20 100644 (file)
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -790,6 +790,7 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
 {
        struct omap8250_priv    *priv = p->port.private_data;
        struct uart_8250_dma    *dma = p->dma;
+       struct dma_tx_state     state;
        unsigned long           flags;
        int ret;
 
@@ -800,10 +801,12 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
                return;
        }
 
-       ret = dmaengine_pause(dma->rxchan);
-       if (WARN_ON_ONCE(ret))
-               priv->rx_dma_broken = true;
-
+       ret = dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+       if (ret == DMA_IN_PROGRESS) {
+               ret = dmaengine_pause(dma->rxchan);
+               if (WARN_ON_ONCE(ret))
+                       priv->rx_dma_broken = true;
+       }
        spin_unlock_irqrestore(&priv->rx_dma_lock, flags);
 
        __dma_rx_do_complete(p);