On Wed, 17 Jun 2015 17:50:01 +0800 Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> 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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
