On Mon, Mar 23, 2020 at 09:07:38PM +0530, Aneesh Kumar K.V wrote: > > This is what I was trying, but considering I am new to DMA subsystem, I > am not sure I got all the details correct. The idea is to look at the > cpu addr and see if that can be used in direct map fashion(is > bus_dma_limit the right restriction here?) if not fallback to dynamic > IOMMU mapping.
I don't think we can throw all these complications into the dma mapping code. At some point I also wonder what the point is, especially for scatterlist mappings, where the iommu can coalesce.