Messages in this thread Patch in this message | | | From | Lars-Peter Clausen <> | Subject | [PATCH 3/3] dmaengine: Fixup dmaengine_prep_slave_single() to be actually useful | Date | Wed, 25 Apr 2012 20:50:53 +0200 |
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From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
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>
--- Changes since v1: * Drop call to sg_set_page * Slightly reword commit message --- include/linux/dmaengine.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 676f967..0e6b595 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -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); -- 1.7.9.5
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