[RFC PATCH 4/7] serial: 8250_dma: enqueue RX dma again on completion.

Sebastian Andrzej Siewior
2014-07-29T19:01:29Z

The omap needs a DMA request pending right away. If it is enqueued once
the bytes are in the FIFO then nothing will happen and the FIFO will be
later purged via RX-timeout interrupt.
This patch requeues RX-DMA request on completion but not if it was
canceled due to the RX-timeout.

Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/tty/serial/8250/8250_core.c | 3 +++
drivers/tty/serial/8250/8250_dma.c | 12 +++++++++---
2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 7a33c30..098ff02 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1556,6 +1556,9 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)

if (!up->dma || dma_err)
status = serial8250_rx_chars(up, status);
+
+ if (dma_err == -ETIMEDOUT && port->type == PORT_OMAP_16750)
+ serial8250_rx_dma(up, 0);
}
serial8250_modem_status(up);
if (!up->dma && (status & UART_LSR_THRE))
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index f9ef69f..acb0a87 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -49,9 +49,8 @@ static void __dma_tx_complete(void *param)
spin_unlock_irqrestore(&p->port.lock, flags);
}

-static void __dma_rx_complete(void *param)
+static void __dma_rx_do_complete(struct uart_8250_port *p, bool timeout)
{
- struct uart_8250_port *p = param;
struct uart_8250_dma *dma = p->dma;
struct tty_port *tty_port = &p->port.state->port;
struct dma_tx_state state;
@@ -67,10 +66,17 @@ static void __dma_rx_complete(void *param)

tty_insert_flip_string(tty_port, dma->rx_buf, count);
p->port.icount.rx += count;
+ if (!timeout && p->port.type == PORT_OMAP_16750)
+ serial8250_rx_dma(p, 0);

tty_flip_buffer_push(tty_port);
}

+static void __dma_rx_complete(void *param)
+{
+ __dma_rx_do_complete(param, false);
+}
+
int serial8250_tx_dma(struct uart_8250_port *p)
{
struct uart_8250_dma *dma = p->dma;
@@ -126,7 +132,7 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
*/
if (dma_status == DMA_IN_PROGRESS) {
dmaengine_pause(dma->rxchan);
- __dma_rx_complete(p);
+ __dma_rx_do_complete(p, true);
}
return -ETIMEDOUT;
default:
--
2.0.1