From 70c9b8bd7ac4931c775dab77ad29117523bf0956 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 11 Jul 2014 17:56:21 +0200 Subject: [PATCH] dmaengine: Clarify device parameter for dma_sync_*_for_*() Signed-off-by: Geert Uytterhoeven Signed-off-by: Vinod Koul --- Documentation/dmaengine.txt | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/Documentation/dmaengine.txt b/Documentation/dmaengine.txt index 2def665..573e28c 100644 --- a/Documentation/dmaengine.txt +++ b/Documentation/dmaengine.txt @@ -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) -- 2.7.4