On Thu, Mar 29, 2018 at 09:58:54PM -0400, Jerome Glisse wrote: > dma_map_resource() is the right API (thought its current implementation > is fill with x86 assumptions). So i would argue that arch can decide to > implement it or simply return dma error address which trigger fallback > path into the caller (at least for GPU drivers). SG variant can be added > on top. It isn't in general. It doesn't integrate with scatterlists (see my comment to page one), and it doesn't integrate with all the subsystems that also need a kernel virtual address.