On Tue, Nov 01, 2022 at 05:32:14PM +0000, Catalin Marinas wrote: > There's also the case of low-end phones with all RAM below 4GB and arm64 > doesn't allocate the swiotlb. Not sure those vendors would go with a > recent kernel anyway. > > So the need for swiotlb now changes from 32-bit DMA to any DMA > (non-coherent but we can't tell upfront when booting, devices may be > initialised pretty late). Yes. The other option would be to use the dma coherent pool for the bouncing, which must be present on non-coherent systems anyway. But it would require us to write a new set of bounce buffering routines.
