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From: bigeasy@linutronix.de (Sebastian Andrzej Siewior)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 10/18] tty: serial: 8250_dma: enqueue RX dma again on completion.
Date: Fri,  5 Sep 2014 21:02:45 +0200
Message-ID: <1409943773-7874-11-git-send-email-bigeasy@linutronix.de> (raw)
In-Reply-To: <1409943773-7874-1-git-send-email-bigeasy@linutronix.de>

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 <bigeasy@linutronix.de>
---
 drivers/tty/serial/8250/8250.h      |  3 ++-
 drivers/tty/serial/8250/8250_core.c |  3 +++
 drivers/tty/serial/8250/8250_dma.c  | 12 +++++++++---
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index a63d198f8d03..fbed1636e9c4 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -80,7 +80,8 @@ struct serial8250_config {
 #define UART_BUG_NOMSR	(1 << 2)	/* UART has buggy MSR status bits (Au1x00) */
 #define UART_BUG_THRE	(1 << 3)	/* UART has buggy THRE reassertion */
 #define UART_BUG_PARITY	(1 << 4)	/* UART mishandles parity if FIFO enabled */
-
+#define UART_BUG_DMA_RX	(1 << 5)	/* UART needs DMA RX req before there is
+					   data in FIFO */
 #define PROBE_RSA	(1 << 0)
 #define PROBE_ANY	(~0)
 
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 2101134e5031..079048db8c81 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1590,6 +1590,9 @@ 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 && up->bugs & UART_BUG_DMA_RX)
+			serial8250_rx_dma(up, 0);
 	}
 	serial8250_modem_status(up);
 	if ((!up->dma || (up->dma && up->dma->tx_err)) &&
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index 69e54abb6e71..3674900a1f14 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->bugs & UART_BUG_DMA_RX)
+		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:
-- 
2.1.0

  parent reply index

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-05 19:02 [PATCH v8 00/18] 8250-core based serial driver for OMAP + DMA Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 01/18] tty: serial: 8250_core: provide a function to export uart_8250_port Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 02/18] tty: serial: 8250_core: allow to overwrite & export serial8250_startup() Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 03/18] tty: serial: 8250_core: allow to set ->throttle / ->unthrottle callbacks Sebastian Andrzej Siewior
2014-09-08 23:33   ` Greg Kroah-Hartman
2014-09-09  0:41     ` Tony Lindgren
2014-09-05 19:02 ` [PATCH 04/18] tty: serial: 8250_core: add run time pm Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 05/18] tty: serial: 8250_core: read only RX if there is something in the FIFO Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 06/18] tty: serial: 8250_core: user the ->line argument as a hint in serial8250_find_match_or_unused() Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 07/18] tty: serial: 8250_core: remove UART_IER_RDI in serial8250_stop_rx() Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 08/18] tty: serial: Add 8250-core based omap driver Sebastian Andrzej Siewior
2014-09-08 16:39   ` Tony Lindgren
2014-09-05 19:02 ` [PATCH 09/18] tty: serial: 8250_dma: handle error on TX submit Sebastian Andrzej Siewior
2014-09-05 19:02 ` Sebastian Andrzej Siewior [this message]
2014-09-05 19:02 ` [PATCH 11/18] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx Sebastian Andrzej Siewior
2014-09-08 16:41   ` Tony Lindgren
2014-09-08 16:45     ` Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 12/18] tty: serial: 8250_dma: optimize the xmit path due to UART_BUG_DMA_TX Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 13/18] tty: serial: 8250_dma: keep own book keeping about RX transfers Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 14/18] tty: serial: 8250_dma: handle the when UART response while DMA remains idle Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 15/18] tty: serial: 8250_dma: add pm runtime Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 16/18] arm: dts: am33xx: add DMA properties for UART Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 17/18] arm: dts: dra7: " Sebastian Andrzej Siewior
2014-09-05 19:02 ` [PATCH 18/18] tty: serial: 8250: omap: add dma support Sebastian Andrzej Siewior
2014-09-08 14:46 ` [PATCH v8 00/18] 8250-core based serial driver for OMAP + DMA Frans Klaver
2014-09-08 15:15   ` Sebastian Andrzej Siewior
2014-09-08 16:33     ` Sebastian Andrzej Siewior
2014-09-08 18:25       ` Frans Klaver
2014-09-08 18:33     ` Frans Klaver
2014-09-09 19:41       ` Sebastian Andrzej Siewior
2014-09-10 14:15         ` Frans Klaver
2014-09-10 16:56           ` Sebastian Andrzej Siewior
2014-09-08 17:40 ` Tony Lindgren
2014-09-08 17:55   ` Tony Lindgren
2014-09-09  7:33     ` Sebastian Andrzej Siewior

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