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serial: sh-sci: Pause DMA engine and get DMA status again 

Occasionally, DMA transaction completes _after_ DMA engine is stopped.
Verify if the transaction has not finished before forcing the engine to
stop and push the data

Signed-off-by: Muhammad Hamza Farooq <mfarooq@visteon.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Muhammad Hamza Farooq 2015-09-18 13:08:32 +02:00 committed by Greg Kroah-Hartman
parent 3b963042b6
commit e7327c09de
1 changed files with 16 additions and 0 deletions
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16
drivers/tty/serial/sh-sci.c
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@ -1277,6 +1277,7 @@ static bool filter(struct dma_chan *chan, void *slave)
static void rx_timer_fn(unsigned long arg)
{
struct sci_port *s = (struct sci_port *)arg;
struct dma_chan *chan = s->chan_rx;
struct uart_port *port = &s->port;
struct dma_tx_state state;
enum dma_status status;
@ -1305,6 +1306,21 @@ static void rx_timer_fn(unsigned long arg)
return;
}
dmaengine_pause(chan);
/*
* sometimes DMA transfer doesn't stop even if it is stopped and
* data keeps on coming until transaction is complete so check
* for DMA_COMPLETE again
* Let packet complete handler take care of the packet
*/
status = dmaengine_tx_status(s->chan_rx, s->active_rx, &state);
if (status == DMA_COMPLETE) {
spin_unlock_irqrestore(&port->lock, flags);
dev_dbg(port->dev, "Transaction complete after DMA engine was stopped");
return;
}
/* Handle incomplete DMA receive */
dmaengine_terminate_all(s->chan_rx);
read = sg_dma_len(&s->sg_rx[active]) - state.residue;