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>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/dma/intel_mid_dma.c b/drivers/dma/intel_mid_dma.c
index d0ef5937fbf6..222e907bfaaa 100644
--- a/drivers/dma/intel_mid_dma.c
+++ b/drivers/dma/intel_mid_dma.c
@@ -394,7 +394,7 @@ static int midc_lli_fill_sg(struct intel_mid_dma_chan *midc,
 			}
 		}
 		/*Populate CTL_HI values*/
-		ctl_hi.ctlx.block_ts = get_block_ts(sg->length,
+		ctl_hi.ctlx.block_ts = get_block_ts(sg_dma_len(sg),
 							desc->width,
 							midc->dma->block_size);
 		/*Populate SAR and DAR values*/
@@ -747,7 +747,7 @@ static struct dma_async_tx_descriptor *intel_mid_dma_prep_slave_sg(
 			txd = intel_mid_dma_prep_memcpy(chan,
 						mids->dma_slave.dst_addr,
 						mids->dma_slave.src_addr,
-						sgl->length,
+						sg_dma_len(sgl),
 						flags);
 			return txd;
 		} else {
@@ -759,7 +759,7 @@ static struct dma_async_tx_descriptor *intel_mid_dma_prep_slave_sg(
 	pr_debug("MDMA: SG Length = %d, direction = %d, Flags = %#lx\n",
 			sg_len, direction, flags);
 
-	txd = intel_mid_dma_prep_memcpy(chan, 0, 0, sgl->length, flags);
+	txd = intel_mid_dma_prep_memcpy(chan, 0, 0, sg_dma_len(sgl), flags);
 	if (NULL == txd) {
 		pr_err("MDMA: Prep memcpy failed\n");
 		return NULL;