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SubjectRe: [PATCH v6 05/14] crypto: marvell/CESA: add TDMA support
On Wed, 17 Jun 2015 17:50:01 +0800
Herbert Xu <herbert@gondor.apana.org.au> wrote:

> On Wed, Jun 17, 2015 at 09:45:33AM +0200, Boris Brezillon wrote:
> >
> > + ret = dma_map_sg(cesa_dev->dev, req->src, creq->src_nents,
> > + DMA_TO_DEVICE);
> > + if (!ret)
> > + return -ENOMEM;
> > +
> > + creq->src_nents = ret;
>
> DMA-API-HOWTO says that you must retain the original nents and
> use it when you call dma_unmap_sg. So I'm afraid one more repost
> is needed :)

My bad (again :-/).
Actually, I think I don't need to save the dma_map_sg return val, since
I'm using the sg_next function to iterate over the scatterlist. Am I
right ?
IOW, is the ->map_sg() function (in dma_map_ops) supposed to merge the
contiguous entries and then flag the unused entries with the is_chain
flag ?
If that's not the case, and the ->map_sg() just marks the merged entries
as empty (length = 0), then I'll have to rework my iterator algorithm.

--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com


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