serial: imx: disable TDMAEN in imx_flush_buffer()

Terminating the DMA, make sure the interrupt is disabled, too.
This fixes random kernel Oops due to dma_tx_call() called for
invalid transmissions.

If we disable the TDMAEN, make sure it's enabled again if a TX
DMA is started.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 0e64f18f8c428ddd82f204082b3c9c12f0499d05..d097169e85d1da77caeddae852f0b20d11a62916 100644 (file)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -502,11 +502,16 @@ static void dma_tx_callback(void *data)
        struct scatterlist *sgl = &sport->tx_sgl[0];
        struct circ_buf *xmit = &sport->port.state->xmit;
        unsigned long flags;
+       unsigned long temp;
 
        spin_lock_irqsave(&sport->port.lock, flags);
 
        dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
 
+       temp = readl(sport->port.membase + UCR1);
+       temp &= ~UCR1_TDMAEN;
+       writel(temp, sport->port.membase + UCR1);
+
        /* update the stat */
        xmit->tail = (xmit->tail + sport->tx_bytes) & (UART_XMIT_SIZE - 1);
        sport->port.icount.tx += sport->tx_bytes;
@@ -539,6 +544,7 @@ static void imx_dma_tx(struct imx_port *sport)
        struct dma_async_tx_descriptor *desc;
        struct dma_chan *chan = sport->dma_chan_tx;
        struct device *dev = sport->port.dev;
+       unsigned long temp;
        int ret;
 
        if (sport->dma_is_txing)
@@ -575,6 +581,11 @@ static void imx_dma_tx(struct imx_port *sport)
 
        dev_dbg(dev, "TX: prepare to send %lu bytes by DMA.\n",
                        uart_circ_chars_pending(xmit));
+
+       temp = readl(sport->port.membase + UCR1);
+       temp |= UCR1_TDMAEN;
+       writel(temp, sport->port.membase + UCR1);
+
        /* fire it */
        sport->dma_is_txing = 1;
        dmaengine_submit(desc);
@@ -1258,6 +1269,7 @@ static void imx_flush_buffer(struct uart_port *port)
 {
        struct imx_port *sport = (struct imx_port *)port;
        struct scatterlist *sgl = &sport->tx_sgl[0];
+       unsigned long temp;
 
        if (!sport->dma_chan_tx)
                return;
@@ -1267,6 +1279,9 @@ static void imx_flush_buffer(struct uart_port *port)
        if (sport->dma_is_txing) {
                dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents,
                             DMA_TO_DEVICE);
+               temp = readl(sport->port.membase + UCR1);
+               temp &= ~UCR1_TDMAEN;
+               writel(temp, sport->port.membase + UCR1);
                sport->dma_is_txing = false;
        }
 }