Re: [PATCH 07/15] tty: serial: 8250_dma: enqueue RX dma again on completion.

[Sebastian Andrzej Siewior]

On 08/18/2014 12:52 PM, One Thousand Gnomes wrote:
> 
>>  if (!up->dma || dma_err)
>>  status = serial8250_rx_chars(up, status);
>> +
>> +if (dma_err && port->type == PORT_OMAP_16750)
>> +serial8250_rx_dma(up, 0);
> 
> Can we stick to a 'has dma' flag and port->rx_dma() type usages so that
> we don't have to rewrite it again to add them the next slightly odd DMA
> user we add 8)

I hide this behind a bug flag, something like UART_NEEDS_DMA_RX_PENDING.

Sebastian
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Re: [PATCH 07/15] tty: serial: 8250_dma: enqueue RX dma again on completion.

[One Thousand Gnomes]

>   if (!up->dma || dma_err)
>   status = serial8250_rx_chars(up, status);
> +
> + if (dma_err && port->type == PORT_OMAP_16750)
> + serial8250_rx_dma(up, 0);

Can we stick to a 'has dma' flag and port->rx_dma() type usages so that
we don't have to rewrite it again to add them the next slightly odd DMA
user we add 8)

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[PATCH 07/15] tty: serial: 8250_dma: enqueue RX dma again on completion.

[Sebastian Andrzej Siewior]

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 enqueues RX-DMA request on completion but not if it was
aborted on error. The first enqueue will happen in the driver in
startup.

Signed-off-by: Sebastian Andrzej Siewior 
---
 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 7498ce1..ab2de27 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1598,6 +1598,9 @@ 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 && port->type == PORT_OMAP_16750)
+   serial8250_rx_dma(up, 0);
}
serial8250_modem_status(up);
if ((!up->dma || up->dma_tx_err) && (status & UART_LSR_THRE))
diff --git a/drivers/tty/serial/8250/8250_dma.c 
b/drivers/tty/serial/8250/8250_dma.c
index 5c59b15..7417ed5 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -50,9 +50,8 @@ 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 error)
 {
-   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;
@@ -68,10 +67,17 @@ static void __dma_rx_complete(void *param)
 
tty_insert_flip_string(tty_port, dma->rx_buf, count);
p->port.icount.rx += count;
+   if (!error && 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;
@@ -139,7 +145,7 @@ 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

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