Using System DMA
Drivers of subordinate DMA devices use one of the following types of system-provided DMA support:
Packet-based DMA, if the driver need not use a system DMA controller's auto-initialize mode. See Using Packet-Based System DMA.
Common-buffer DMA, if the driver does use the auto-initialize mode. See Using Common-Buffer System DMA.
In addition, any driver that uses packet-based DMA can use support routines intended to streamline scatter/gather DMA, regardless of whether its device has built-in scatter/gather support. See Using Scatter/Gather DMA for details.