On Thu, Jun 18, 2015 at 10:04:00AM +0100, Russell King - ARM Linux wrote:

If dma_map_sg() coalesces scatterlist entries, then ret will be smaller
than src_nents, and ret indicates how many scatterlist entries to be
walked during DMA - you should not use src_nents for that.  I couldn't
see where the driver used that information.  In fact, the driver seems
to be capable of walking more than src_nents/ret numbers of scatterlist
entries: it just keeps going with sg_next() until it hits the end of
the allocated scatterlist.

I think he should be OK even though he throws away the return value
because he's stopping his walk once the sum of sg_dma_length reaches
his end goal.

Cheers,
-- 
Email: Herbert Xu [off-list ref]
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