The omap needs a DMA request pending right away. If it is enqueued once
the bytes are in the FIFO then nothing will happen and the FIFO will be
later purged via RX-timeout interrupt.
This patch enqueues RX-DMA request on completion but not if it was
aborted on error. The first enqueue will happen in the driver in
startup.

Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
 drivers/tty/serial/8250/8250_core.c |  3 +++
 drivers/tty/serial/8250/8250_dma.c  | 12 +++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c 
b/drivers/tty/serial/8250/8250_core.c
index 7498ce1..ab2de27 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1598,6 +1598,9 @@ int serial8250_handle_irq(struct uart_port *port, 
unsigned int iir)
 
                if (!up->dma || dma_err)
                        status = serial8250_rx_chars(up, status);
+
+               if (dma_err && port->type == PORT_OMAP_16750)
+                       serial8250_rx_dma(up, 0);
        }
        serial8250_modem_status(up);
        if ((!up->dma || up->dma_tx_err) && (status & UART_LSR_THRE))
diff --git a/drivers/tty/serial/8250/8250_dma.c 
b/drivers/tty/serial/8250/8250_dma.c
index 5c59b15..7417ed5 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -50,9 +50,8 @@ static void __dma_tx_complete(void *param)
        spin_unlock_irqrestore(&p->port.lock, flags);
 }
 
-static void __dma_rx_complete(void *param)
+static void __dma_rx_do_complete(struct uart_8250_port *p, bool error)
 {
-       struct uart_8250_port   *p = param;
        struct uart_8250_dma    *dma = p->dma;
        struct tty_port         *tty_port = &p->port.state->port;
        struct dma_tx_state     state;
@@ -68,10 +67,17 @@ static void __dma_rx_complete(void *param)
 
        tty_insert_flip_string(tty_port, dma->rx_buf, count);
        p->port.icount.rx += count;
+       if (!error && p->port.type == PORT_OMAP_16750)
+               serial8250_rx_dma(p, 0);
 
        tty_flip_buffer_push(tty_port);
 }
 
+static void __dma_rx_complete(void *param)
+{
+       __dma_rx_do_complete(param, false);
+}
+
 int serial8250_tx_dma(struct uart_8250_port *p)
 {
        struct uart_8250_dma            *dma = p->dma;
@@ -139,7 +145,7 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned 
int iir)
                 */
                if (dma_status == DMA_IN_PROGRESS) {
                        dmaengine_pause(dma->rxchan);
-                       __dma_rx_complete(p);
+                       __dma_rx_do_complete(p, true);
                }
                return -ETIMEDOUT;
        default:
-- 
2.0.1

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