From: Kuninori Morimoto Date: Wed, 25 Apr 2012 18:50:53 +0000 (+0200) Subject: dmaengine: Fixup dmaengine_prep_slave_single() to be actually useful X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=922ee08baad2052d0759f100e026d49798c51fef;p=linux-beck.git dmaengine: Fixup dmaengine_prep_slave_single() to be actually useful 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 Signed-off-by: Lars-Peter Clausen Acked-by: Linus Walleij Signed-off-by: Vinod Koul --- diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 676f967390ae..0e6b595e95c8 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);