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From: Vignesh R <vigneshr@ti.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>,
	Peter Hurley <peter@hurleysoftware.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	<linux-serial@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-omap@vger.kernel.org>, Vignesh R <vigneshr@ti.com>
Subject: [PATCH 1/3] serial: 8250: omap: pause DMA only if DMA transfer in progress
Date: Fri, 13 Jan 2017 13:31:59 +0530	[thread overview]
Message-ID: <20170113080201.6515-2-vigneshr@ti.com> (raw)
In-Reply-To: <20170113080201.6515-1-vigneshr@ti.com>

It is possible that DMA transfer is already complete but, completion
handler is yet to be called, when dmaengine_pause() is called in case of
error condition(like break/rx timeout). This leads to dmaengine_pause()
API to return EINVAL (as descriptor is already NULL) causing
rx_dma_broken flag to be set and effectively disabling RX DMA.
Fix this by calling dmaengine_pause() only when transfer is in progress.

Signed-off-by: Vignesh R <vigneshr@ti.com>
---
 drivers/tty/serial/8250/8250_omap.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 61ad6c3b20a0..4ad1934ef6ed 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -790,6 +790,7 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
 {
 	struct omap8250_priv	*priv = p->port.private_data;
 	struct uart_8250_dma	*dma = p->dma;
+	struct dma_tx_state     state;
 	unsigned long		flags;
 	int ret;
 
@@ -800,10 +801,12 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
 		return;
 	}
 
-	ret = dmaengine_pause(dma->rxchan);
-	if (WARN_ON_ONCE(ret))
-		priv->rx_dma_broken = true;
-
+	ret = dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+	if (ret == DMA_IN_PROGRESS) {
+		ret = dmaengine_pause(dma->rxchan);
+		if (WARN_ON_ONCE(ret))
+			priv->rx_dma_broken = true;
+	}
 	spin_unlock_irqrestore(&priv->rx_dma_lock, flags);
 
 	__dma_rx_do_complete(p);
-- 
2.11.0

WARNING: multiple messages have this Message-ID (diff)
From: Vignesh R <vigneshr@ti.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>,
	Peter Hurley <peter@hurleysoftware.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-omap@vger.kernel.org, Vignesh R <vigneshr@ti.com>
Subject: [PATCH 1/3] serial: 8250: omap: pause DMA only if DMA transfer in progress
Date: Fri, 13 Jan 2017 13:31:59 +0530	[thread overview]
Message-ID: <20170113080201.6515-2-vigneshr@ti.com> (raw)
In-Reply-To: <20170113080201.6515-1-vigneshr@ti.com>

It is possible that DMA transfer is already complete but, completion
handler is yet to be called, when dmaengine_pause() is called in case of
error condition(like break/rx timeout). This leads to dmaengine_pause()
API to return EINVAL (as descriptor is already NULL) causing
rx_dma_broken flag to be set and effectively disabling RX DMA.
Fix this by calling dmaengine_pause() only when transfer is in progress.

Signed-off-by: Vignesh R <vigneshr@ti.com>
---
 drivers/tty/serial/8250/8250_omap.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 61ad6c3b20a0..4ad1934ef6ed 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -790,6 +790,7 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
 {
 	struct omap8250_priv	*priv = p->port.private_data;
 	struct uart_8250_dma	*dma = p->dma;
+	struct dma_tx_state     state;
 	unsigned long		flags;
 	int ret;
 
@@ -800,10 +801,12 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
 		return;
 	}
 
-	ret = dmaengine_pause(dma->rxchan);
-	if (WARN_ON_ONCE(ret))
-		priv->rx_dma_broken = true;
-
+	ret = dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
+	if (ret == DMA_IN_PROGRESS) {
+		ret = dmaengine_pause(dma->rxchan);
+		if (WARN_ON_ONCE(ret))
+			priv->rx_dma_broken = true;
+	}
 	spin_unlock_irqrestore(&priv->rx_dma_lock, flags);
 
 	__dma_rx_do_complete(p);
-- 
2.11.0

  reply	other threads:[~2017-01-13  8:03 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-13  8:01 [PATCH 0/3] tty: serial: 8250_omap: Enable DMA support Vignesh R
2017-01-13  8:01 ` Vignesh R
2017-01-13  8:01 ` Vignesh R [this message]
2017-01-13  8:01   ` [PATCH 1/3] serial: 8250: omap: pause DMA only if DMA transfer in progress Vignesh R
2017-01-13  8:02 ` [PATCH 2/3] tty: serial: 8250_omap: Add OMAP_DMA_TX_KICK quirk for AM437x Vignesh R
2017-01-13  8:02   ` Vignesh R
2017-01-13  8:02 ` [PATCH 3/3] tty: serial: 8250_omap: Remove rx_dma_broken flag Vignesh R
2017-01-13  8:02   ` Vignesh R
2017-01-13 18:20 ` [PATCH 0/3] tty: serial: 8250_omap: Enable DMA support Tony Lindgren
2017-01-17  6:06   ` Vignesh R
2017-01-17 10:05     ` Vignesh R
2017-01-17 23:25       ` Tony Lindgren
2017-01-18 12:04         ` Vignesh R
2017-01-18 17:07           ` Tony Lindgren
2017-01-19 13:24   ` Greg Kroah-Hartman
2017-01-19 14:54     ` Tony Lindgren
2017-01-19 15:35       ` Greg Kroah-Hartman
2017-01-20  8:22         ` Vignesh R

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