Re: sg_dma_page_iter offset & length considerations

[Christoph Hellwig]

Given that mmc uses block layer helpers to build the sg list you
just have to set the right block layer and DMA layer (in case an
iommu merges during map_sg) dma_boundary paramters (PAGE_SIZE - 1),
and you should get sglists formatted to your requirements, no need
to use an iterator.