On Wed, Jun 17, 2015 at 01:05:27PM +0800, Herbert Xu wrote:

On Tue, Jun 16, 2015 at 11:58:59AM +0200, Boris Brezillon wrote:

quoted

+	ret = dma_map_sg(cesa_dev->dev, req->src, creq->src_nents,
+			 DMA_TO_DEVICE);
+	if (ret != creq->src_nents)
+		return -ENOMEM;

Hmm it doesn't quite work like that.  It returns zero on error,
otherwise it returns the number (n) of mapped entries which may be
less than what you gave it due to merging.  You're then supposed
to use only the first n entries which should contain everything.

Please take a look at Documentation/DMA-API-HOWTO.txt, it has
everything you need to know about the dma_map_sg interface.

Cheers,
-- 
Email: Herbert Xu [off-list ref]
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