serial: sh-sci: Do not resubmit DMA descriptors

Resubmission of DMA descriptors is explicitly forbidden by the DMA
engine API.

Hence pass DMA_CTRL_ACK to dmaengine_prep_slave_sg(), and prepare a new
DMA descriptor instead of reusing the old one.
Remove sci_port.desc_rx[], as there's no longer a need to access the
active descriptor.

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 9c2bc0f23d3af08c27b6981c73c3cbd382bb8c2a..e318f002da399e70862a504575f6d1fdf74598a0 100644 (file)
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -104,7 +104,6 @@ struct sci_port {
        struct dma_chan                 *chan_rx;
 
 #ifdef CONFIG_SERIAL_SH_SCI_DMA
-       struct dma_async_tx_descriptor  *desc_rx[2];
        dma_cookie_t                    cookie_tx;
        dma_cookie_t                    cookie_rx[2];
        dma_cookie_t                    active_rx;
@@ -1397,11 +1396,11 @@ static void sci_submit_rx(struct sci_port *s)
                struct dma_async_tx_descriptor *desc;
 
                desc = dmaengine_prep_slave_sg(chan,
-                       sg, 1, DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
+                       sg, 1, DMA_DEV_TO_MEM,
+                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                if (!desc)
                        goto fail;
 
-               s->desc_rx[i] = desc;
                desc->callback = sci_dma_rx_complete;
                desc->callback_param = s;
                s->cookie_rx[i] = dmaengine_submit(desc);
@@ -1420,10 +1419,8 @@ static void sci_submit_rx(struct sci_port *s)
 fail:
        if (i)
                dmaengine_terminate_all(chan);
-       for (i = 0; i < 2; i++) {
-               s->desc_rx[i] = NULL;
+       for (i = 0; i < 2; i++)
                s->cookie_rx[i] = -EINVAL;
-       }
        s->active_rx = -EINVAL;
        dev_warn(s->port.dev, "Failed to re-start Rx DMA, using PIO\n");
        sci_rx_dma_release(s, true);
@@ -1447,7 +1444,6 @@ static void work_fn_rx(struct work_struct *work)
                        s->active_rx);
                return;
        }
-       desc = s->desc_rx[new];
 
        status = dmaengine_tx_status(s->chan_rx, s->active_rx, &state);
        if (status != DMA_COMPLETE) {
@@ -1474,17 +1470,27 @@ static void work_fn_rx(struct work_struct *work)
                return;
        }
 
+       desc = dmaengine_prep_slave_sg(s->chan_rx, &s->sg_rx[new], 1,
+                                      DMA_DEV_TO_MEM,
+                                      DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+       if (!desc)
+               goto fail;
+
+       desc->callback = sci_dma_rx_complete;
+       desc->callback_param = s;
        s->cookie_rx[new] = dmaengine_submit(desc);
-       if (dma_submit_error(s->cookie_rx[new])) {
-               dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
-               sci_rx_dma_release(s, true);
-               return;
-       }
+       if (dma_submit_error(s->cookie_rx[new]))
+               goto fail;
 
        s->active_rx = s->cookie_rx[!new];
 
        dev_dbg(port->dev, "%s: cookie %d #%d, new active cookie %d\n",
                __func__, s->cookie_rx[new], new, s->active_rx);
+       return;
+
+fail:
+       dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
+       sci_rx_dma_release(s, true);
 }
 
 static void work_fn_tx(struct work_struct *work)