Aug. 31, 2018
12:53 a.m.
Hi everyone, Thank for your time, I'm new to linux kernel. I am reading LDD3 chapter 15, Dirrect Memory Access section. I see that when I call function /dma_map_single/ and /dma_unmap_single/, I need to pass a direction as a parameter. I wonder what is purpose of it? Does It relate to something like permission? Can I call /dma_map_single /with DMA_BIDIRECTIONAL and then call /dma_unmap_single /with DMA_TO_DEVICE? Will it cause any problem? Thank you very much.