I think we just need to byte the bullet and move over arm to dma-direct
entirely. This needs a careful audit of what differs, but the biggest
item is that we need to ensure dmabounce keeps working (or is replaced
with swiotlb in a suitable way, but that might be a lot more work).
_
ARM devices might use the arch's custom dma-mapping implementation or
dma-direct/swiotlb depending on how the kernel is built. This is not
good enough as we need to be able to control the device's DMA ops based
on the specific machine configuration.
Centralise control over DMA ops with arm_dma_dir
