- use dev_dbg for device-centric debugging messages
- use pr_debug for general debugging messages
- use dmapools instead of pcipools
- use NULL rather than 0 for NULL pointers
- use enum dma_data_direction rather than int
- use DMA_* direction definitions rather than PCI_DMA_*
- only check for sane DMA direction on mapping functions, but
  check that DMA direction matches when unmapping/syncing.