Pull dma mapping updates from Christoph Hellwig:
 "First batch of dma-mapping changes for 4.20.

  There will be a second PR as some big changes were only applied just
  before the end of the merge window, and I want to give them a few more
  days in linux-next.

  Summary:

   - mostly more consolidation of the direct mapping code, including
     converting over hexagon, and merging the coherent and non-coherent
     code into a single dma_map_ops instance (me)

   - cleanups for the dma_configure/dma_unconfigure callchains (me)

   - better handling of dma_masks in odd setups (me, Alexander Duyck)

   - better debugging of passing vmalloc address to the DMA API (Stephen
     Boyd)

   - CMA command line parsing fix (He Zhe)"

* tag 'dma-mapping-4.20' of git://git.infradead.org/users/hch/dma-mapping: (27 commits)
  dma-direct: respect DMA_ATTR_NO_WARN
  dma-mapping: translate __GFP_NOFAIL to DMA_ATTR_NO_WARN
  dma-direct: document the zone selection logic
  dma-debug: Check for drivers mapping invalid addresses in dma_map_single()
  dma-direct: fix return value of dma_direct_supported
  dma-mapping: move dma_default_get_required_mask under ifdef
  dma-direct: always allow dma mask <= physiscal memory size
  dma-direct: implement complete bus_dma_mask handling
  dma-direct: refine dma_direct_alloc zone selection
  dma-direct: add an explicit dma_direct_get_required_mask
  dma-mapping: make the get_required_mask method available unconditionally
  unicore32: remove swiotlb support
  Revert "dma-mapping: clear dev->dma_ops in arch_teardown_dma_ops"
  dma-mapping: support non-coherent devices in dma_common_get_sgtable
  dma-mapping: consolidate the dma mmap implementations
  dma-mapping: merge direct and noncoherent ops
  dma-mapping: move the dma_coherent flag to struct device
  MIPS: don't select DMA_MAYBE_COHERENT from DMA_PERDEV_COHERENT
  dma-mapping: add the missing ARCH_HAS_SYNC_DMA_FOR_CPU_ALL declaration
  dma-mapping: fix panic caused by passing empty cma command line argument
  ...