On 23-04-21, 11:17, Lars-Peter Clausen wrote:

It seems to me what we are missing from the DMAengine API is the equivalent
of device_prep_dma_memcpy() that is able to take SG lists. There is already
a memset_sg, it should be possible to add something similar for memcpy.

You mean something like dmaengine_prep_dma_sg() which was removed?

static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_sg(
               struct dma_chan *chan,
               struct scatterlist *dst_sg, unsigned int dst_nents,
               struct scatterlist *src_sg, unsigned int src_nents,
               unsigned long flags)

The problem with this API is that it would work only when src_sg and
dst_sg is of similar nature, if not then how should one go about
copying...should we fill without a care for dst_sg being different than
src_sg as long as total data to be copied has enough space in dst...

We can always add this back if we have in-kernel user but the semantics
of the API needs to be thought thru

Thanks
-- 
~Vinod

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