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| author |   Dirk Behme <dirk.behme@de.bosch.com> | 2014-12-09 18:11:28 +0900 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-01-09 14:23:07 -0800 |
| commit | 42f752b3fbcfee9c27e4f6f6216e60e130ba98c8 (patch) | |
| tree | 26b286ca4a8d33dde817da74cff71b8146151213 /drivers/tty/serial/imx.c | |
| parent | serial: imx: unmap scatter gather list in imx_flush_buffer (diff) | |
| download | linux-dev-42f752b3fbcfee9c27e4f6f6216e60e130ba98c8.tar.xz linux-dev-42f752b3fbcfee9c27e4f6f6216e60e130ba98c8.zip | |
serial: imx: use dma_is_txing to synchronize dma_tx_callback and imx_dma_tx
To synchronize between dma_tx_callback() and imx_dma_tx() use the same
variable, dma_is_txing. This prevents any race between these two functions
and ensures that a new DMA can start only after the first has been
finished.
Before the new DMA can be set up, update the circular buffer logic, first.
Therefore, change dma_is_txing after that update, instead of before.
While doing this, in dma_tx_callback() extend the locking to dma_unmap_sg()
and the update of dma_is_txing.
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/imx.c')
| -rw-r--r-- | drivers/tty/serial/imx.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 952730ab9067..1c4f367b6fb6 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -502,18 +502,20 @@ static void dma_tx_callback(void *data) struct circ_buf *xmit = &sport->port.state->xmit; unsigned long flags; - dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE); + spin_lock_irqsave(&sport->port.lock, flags); - sport->dma_is_txing = 0; + dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE); /* update the stat */ - spin_lock_irqsave(&sport->port.lock, flags); xmit->tail = (xmit->tail + sport->tx_bytes) & (UART_XMIT_SIZE - 1); sport->port.icount.tx += sport->tx_bytes; - spin_unlock_irqrestore(&sport->port.lock, flags); dev_dbg(sport->port.dev, "we finish the TX DMA.\n"); + sport->dma_is_txing = 0; + + spin_unlock_irqrestore(&sport->port.lock, flags); + uart_write_wakeup(&sport->port); if (waitqueue_active(&sport->dma_wait)) { @@ -530,11 +532,9 @@ 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; - enum dma_status status; int ret; - status = dmaengine_tx_status(chan, (dma_cookie_t)0, NULL); - if (DMA_IN_PROGRESS == status) + if (sport->dma_is_txing) return; sport->tx_bytes = uart_circ_chars_pending(xmit); |