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dmaengine: Fixup dmaengine_prep_slave_single() to be actually useful

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dmaengine_prep_slave_single() is a helper function which is supposed to be used
to prepare a transfer of a single contingous buffer. Currently the function
takes a pointer to such a buffer from which it builds a scatterlist and passes
it on to device_prep_slave_sg. The dmaengine framework requires that any
scatterlist that is passed to device_prep_slave_sg is mapped and it may not be
unmapped until the DMA operation has completed. This is not the here and any use
of dmaengine_prep_slave_single() will lead to undefined behaviour (Most likely a
system crash).

This patch changes dmaengine_prep_slave_single() to take a dma_addr_t instead of
a pointer to a buffer and moves the responsibility of mapping and unmapping the
buffer up to the caller.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
This commit is contained in:
Kuninori Morimoto 2012-04-25 20:50:53 +02:00 committed by Vinod Koul
parent fdaf9c4b22
commit 922ee08baa
1 changed files with 4 additions and 2 deletions
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6
include/linux/dmaengine.h
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@ -615,11 +615,13 @@ static inline int dmaengine_slave_config(struct dma_chan *chan,
}
static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_single(
struct dma_chan *chan, void *buf, size_t len,
struct dma_chan *chan, dma_addr_t buf, size_t len,
enum dma_transfer_direction dir, unsigned long flags)
{
struct scatterlist sg;
sg_init_one(&sg, buf, len);
sg_init_table(&sg, 1);
sg_dma_address(&sg) = buf;
sg_dma_len(&sg) = len;
return chan->device->device_prep_slave_sg(chan, &sg, 1,
dir, flags, NULL);