serial: sh-sci: Pause DMA engine and get DMA status again

Occasionally, DMA transaction completes _after_ DMA engine is stopped.
Verify if the transaction has not finished before forcing the engine to
stop and push the data

Signed-off-by: Muhammad Hamza Farooq <mfarooq@visteon.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 9406fe227bc76c96da8ce78fe8e93c8bbfc30e1c..b1d1ce1986e6c0647d70b7d02e0d1838f5bd6007 100644 (file)
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1277,6 +1277,7 @@ static bool filter(struct dma_chan *chan, void *slave)
 static void rx_timer_fn(unsigned long arg)
 {
        struct sci_port *s = (struct sci_port *)arg;
+       struct dma_chan *chan = s->chan_rx;
        struct uart_port *port = &s->port;
        struct dma_tx_state state;
        enum dma_status status;
@@ -1305,6 +1306,21 @@ static void rx_timer_fn(unsigned long arg)
                return;
        }
 
+       dmaengine_pause(chan);
+
+       /*
+        * sometimes DMA transfer doesn't stop even if it is stopped and
+        * data keeps on coming until transaction is complete so check
+        * for DMA_COMPLETE again
+        * Let packet complete handler take care of the packet
+        */
+       status = dmaengine_tx_status(s->chan_rx, s->active_rx, &state);
+       if (status == DMA_COMPLETE) {
+               spin_unlock_irqrestore(&port->lock, flags);
+               dev_dbg(port->dev, "Transaction complete after DMA engine was stopped");
+               return;
+       }
+
        /* Handle incomplete DMA receive */
        dmaengine_terminate_all(s->chan_rx);
        read = sg_dma_len(&s->sg_rx[active]) - state.residue;