On Wed, 17 Jun 2015 13:56:33 +0800 Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: > 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. Yep, I read it, but apparently not carefully enough ;-). I'll fix that. Note that I did not ignore your previous comment on purpose (checking for !ret to verify if the sg entries were successfully mapped), but I have a specific case in the hash code where the requested len is 0 (final request) and thus the src_nents is 0 too. Which means I'm expecting the dma_sg_map to return 0. Anyway, now I'm doing the following test: if (creq->src_nents && !ret) return -ENOMEM; Best Regards, Boris -- 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
