serial: sh-sci: Resume PIO in sci_rx_interrupt() on DMA failure

On (H)SCIF, sci_submit_rx() is called in the receive interrupt handler.
Hence if DMA submission fails, the interrupt handler should resume
handling reception using PIO, else no more data is received.

Make sci_submit_rx() return an error indicator, so the receive interrupt
handler can act appropriately.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
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 e353e03ce2602559e605f8610952bc97178d627b..8df0fd8245203f8b5d77aa6f5f8666830ca47b01 100644 (file)
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1331,7 +1331,7 @@ static void sci_tx_dma_release(struct sci_port *s)
        dma_release_channel(chan);
 }
 
-static void sci_submit_rx(struct sci_port *s, bool port_lock_held)
+static int sci_submit_rx(struct sci_port *s, bool port_lock_held)
 {
        struct dma_chan *chan = s->chan_rx;
        struct uart_port *port = &s->port;
@@ -1359,7 +1359,7 @@ static void sci_submit_rx(struct sci_port *s, bool port_lock_held)
        s->active_rx = s->cookie_rx[0];
 
        dma_async_issue_pending(chan);
-       return;
+       return 0;
 
 fail:
        /* Switch to PIO */
@@ -1374,6 +1374,7 @@ fail:
        sci_start_rx(port);
        if (!port_lock_held)
                spin_unlock_irqrestore(&port->lock, flags);
+       return -EAGAIN;
 }
 
 static void work_fn_tx(struct work_struct *work)
@@ -1668,8 +1669,10 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
                        disable_irq_nosync(irq);
                        scr |= SCSCR_RDRQE;
                } else {
+                       if (sci_submit_rx(s, false) < 0)
+                               goto handle_pio;
+
                        scr &= ~SCSCR_RIE;
-                       sci_submit_rx(s, false);
                }
                serial_port_out(port, SCSCR, scr);
                /* Clear current interrupt */
@@ -1681,6 +1684,8 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
 
                return IRQ_HANDLED;
        }
+
+handle_pio:
 #endif
 
        if (s->rx_trigger > 1 && s->rx_fifo_timeout > 0) {