linux-kernel - [PATCH 3/4] dma: mxs-dma: make mxs_dma_prep_slave

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Message-Id: <fd785eed4c58e0ee591084aa5334cafcc8cfe082.1323176362.git.LW@KARO-electronics.de>
Date:	Thu,  8 Dec 2011 09:15:43 +0100
From:	Lothar Waßmann <LW@...O-electronics.de>
To:	Vinod Koul <vinod.koul@...el.com>
Cc:	Huang Shijie <b32955@...escale.com>,
	Wolfram Sang <w.sang@...gutronix.de>,
	linux-kernel@...r.kernel.org,
	Lothar Waßmann <LW@...O-electronics.de>
Subject: [PATCH 3/4] dma: mxs-dma: make mxs_dma_prep_slave_sg() multi user safe

Using a static variable for counting the number of CCWs attached to
a DMA channel when appending a new descriptor is not multi user safe.

Signed-off-by: Lothar Waßmann <LW@...O-electronics.de>
---
 drivers/dma/mxs-dma.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
index c7574e8..78336b0 100644
--- a/drivers/dma/mxs-dma.c
+++ b/drivers/dma/mxs-dma.c
@@ -111,6 +111,7 @@ struct mxs_dma_chan {
 	int				chan_irq;
 	struct mxs_dma_ccw		*ccw;
 	dma_addr_t			ccw_phys;
+	int				desc_count;
 	dma_cookie_t			last_completed;
 	enum dma_status			status;
 	unsigned int			flags;
@@ -386,7 +387,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
 	struct scatterlist *sg;
 	int i, j;
 	u32 *pio;
-	static int idx;
+	int idx = append ? mxs_chan->desc_count : 0;
 
 	if (mxs_chan->status == DMA_IN_PROGRESS && !append)
 		return NULL;
@@ -462,6 +463,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
 			}
 		}
 	}
+	mxs_chan->desc_count = idx;
 
 	return &mxs_chan->desc;
 
@@ -523,6 +525,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_dma_cyclic(
 
 		i++;
 	}
+	mxs_chan->desc_count = i;
 
 	return &mxs_chan->desc;
 
-- 
1.5.6.5

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