Re: [PATCH v5 05/14] crypto: marvell/CESA: add TDMA support

[Herbert Xu]

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:
> >
> > +	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 <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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