dma direction

Hello, I read the DMA-API-HOWTO https://www.kernel.org/doc/Documentation/DMA-API-HOWTO.txt Which mainly talks about dma mapping APIs. But I don't understand what's the meaning of DMA direction in context of mapping. As I understand this documentation talks about mapping of dma buffers - NOT about triggering dma copy. In order to do a dma copy, we should use sometlink like dmaengine, Right ? So if dma mapping is not concerned with copying dma from cpu to device (or vice versa), why does it talks about dma direction ? Thanks, Ran