From fdaf9c4b22247a6cc6cda9459be3e52764c14d95 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Wed, 25 Apr 2012 20:50:52 +0200 Subject: dmaengine: Use dma_sg_len(sg) instead of sg->length sg->length may or may not contain the length of the dma region to transfer, depending on the architecture - dma_sg_len(sg) always will though. For the architectures which use the drivers modified by this patch it probably is the case that sg->length contains the dma transfer length. But to be consistent and future proof change them to use dma_sg_len. To quote Russel King: sg->length is meaningless to something performing DMA. In cases where sg_dma_len(sg) and sg->length are the same storage, then there's no problem. But scatterlists _can_ (and one some architectures) do split them - especially when you have an IOMMU which can allow you to combine a scatterlist into fewer entries. So, anything using sg->length for the size of a scatterlist's DMA transfer _after_ a call to dma_map_sg() is almost certainly buggy. The patch has been generated using the following coccinelle patch: @@ struct scatterlist *sg; expression X; @@ -sg[X].length +sg_dma_len(&sg[X]) @@ struct scatterlist *sg; @@ -sg->length +sg_dma_len(sg) Signed-off-by: Lars-Peter Clausen Acked-by: Linus Walleij Signed-off-by: Vinod Koul --- drivers/dma/mxs-dma.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/dma/mxs-dma.c') diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c index 655d4ce6ed0..3db3a48d3f0 100644 --- a/drivers/dma/mxs-dma.c +++ b/drivers/dma/mxs-dma.c @@ -415,9 +415,9 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg( ccw->bits |= BF_CCW(MXS_DMA_CMD_NO_XFER, COMMAND); } else { for_each_sg(sgl, sg, sg_len, i) { - if (sg->length > MAX_XFER_BYTES) { + if (sg_dma_len(sg) > MAX_XFER_BYTES) { dev_err(mxs_dma->dma_device.dev, "maximum bytes for sg entry exceeded: %d > %d\n", - sg->length, MAX_XFER_BYTES); + sg_dma_len(sg), MAX_XFER_BYTES); goto err_out; } @@ -425,7 +425,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg( ccw->next = mxs_chan->ccw_phys + sizeof(*ccw) * idx; ccw->bufaddr = sg->dma_address; - ccw->xfer_bytes = sg->length; + ccw->xfer_bytes = sg_dma_len(sg); ccw->bits = 0; ccw->bits |= CCW_CHAIN; -- cgit v1.2.3-18-g5258