[PATCH v2 1/2] dmaengine: Clarify device parameter for dma_sync_*_for_*()
From: Geert Uytterhoeven
Date: Fri Jul 11 2014 - 11:56:36 EST
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Documentation/dmaengine.txt | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/Documentation/dmaengine.txt b/Documentation/dmaengine.txt
index 879b6e31e2da..87d3f192e160 100644
@@ -100,8 +100,10 @@ The slave DMA usage consists of following steps:
The peripheral driver is expected to have mapped the scatterlist for
the DMA operation prior to calling device_prep_slave_sg, and must
keep the scatterlist mapped until the DMA operation has completed.
- The scatterlist must be mapped using the DMA struct device. So,
- normal setup should look like this:
+ The scatterlist must be mapped using the DMA struct device.
+ If a mapping needs to be synchronized later, dma_sync_*_for_*() must be
+ called using the DMA struct device, too.
+ So, normal setup should look like this:
nr_sg = dma_map_sg(chan->device->dev, sgl, sg_len);
if (nr_sg == 0)
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