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:
<smpl>
@@
struct scatterlist *sg;
expression X;
@@
-sg[X].length
+sg_dma_len(&sg[X])
@@
struct scatterlist *sg;
@@
-sg->length
+sg_dma_len(sg)
</smpl>
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>
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index 003220a..49ecbbb 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -1328,7 +1328,7 @@
int ret, tmp;
dev_dbg(&pl08x->adev->dev, "%s prepare transaction of %d bytes from %s\n",
- __func__, sgl->length, plchan->name);
+ __func__, sg_dma_len(sgl), plchan->name);
txd = pl08x_get_txd(plchan, flags);
if (!txd) {