linux-kernel - [PATCH 2/3] dmaenegine: edma: allow pause/resume for non-cyclic mode

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Message-ID: <87vbghaiva.fsf@linutronix.de>
Date:	Mon, 27 Apr 2015 13:52:25 +0200
From:	John Ogness <john.ogness@...utronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 2/3] dmaenegine: edma: allow pause/resume for non-cyclic mode

The 8250_omap serial driver relies on dmaengine_pause() actually
pausing the DMA transfer. Before this patch dmaengine_pause() is
a NOP for non-cylic DMA transfers. This allowed the 8250_omap
driver to read DMA buffers while the DMA was still active,
resulting in lost serial data.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 drivers/dma/edma.c |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index bf09db7..88853af 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -300,8 +300,7 @@ static int edma_dma_pause(struct dma_chan *chan)
 {
 	struct edma_chan *echan = to_edma_chan(chan);
 
-	/* Pause/Resume only allowed with cyclic mode */
-	if (!echan->edesc || !echan->edesc->cyclic)
+	if (!echan->edesc)
 		return -EINVAL;
 
 	edma_pause(echan->ch_num);
@@ -312,10 +311,6 @@ static int edma_dma_resume(struct dma_chan *chan)
 {
 	struct edma_chan *echan = to_edma_chan(chan);
 
-	/* Pause/Resume only allowed with cyclic mode */
-	if (!echan->edesc->cyclic)
-		return -EINVAL;
-
 	edma_resume(echan->ch_num);
 	return 0;
 }
-- 
1.7.10.4
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