Messages in this thread | | | Date | Wed, 13 Feb 2008 20:24:02 +0100 | From | Haavard Skinnemoen <> | Subject | Re: [RFC v3 4/7] dmaengine: Add slave DMA interface |
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On Wed, 13 Feb 2008 12:07:26 -0700 "Dan Williams" <dan.j.williams@intel.com> wrote:
> > +struct dma_slave_descriptor { > > + struct dma_async_tx_descriptor txd; > > + struct list_head client_node; > > +}; > > Can you explain a bit why client_node is needed? I do not think we > need dma_slave_descriptor if dma_unmap data / control is added to > dma_async_tx_descriptor. Hmm?
Well, it's perhaps not needed for slave transfers as such. But the MMC driver (and I suspect quite a few other users of the slave interface) deals with scatterlists, so it needs a way to keep track of all the descriptors it submits. Hence the list node.
But looking at your latest patch series, I guess we can use the new "next" field instead. It's not like we really need the full capabilities of list_head.
Haavard
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