hi: 2010/8/31 Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx>: > Quite challenging.... here's some thoughts... > > On Mon, Aug 30, 2010 at 15:44, loody <miloody@xxxxxxxxx> wrote: >> Dear all: >> There are some questions about dma api when I read the document: >> 1. should dma apis in dma_mapping.h be implemented by different arch? > > The question is: are all architectures has DMA? for the same reason x86 has it? > > I mean here is, DMA is invented to cut the CPU load (read: sometimes > CPU is not involved at all, only at the setup of transaction) during > data transfer between memory and devices...but, let's say arch X can > do it so efficiently even CPU is still in the game.....then I am not > surprised we see no DMA there... > > And...maybe in other architecture it's not named DMA? > > PS: thus makes me think, in embedded archs, perhaps it can be done quite fast... > thanks for your explanation, btw I saw the document you wrote on full circle. It's GREAT~~ There 5 Dmas on my embedded system and I try to implement the Kernel Api for them to use. But I have no idea what are they used for ? after reading the dma-api.txt. 1. It seems some function used for memory coherent, other are no, such us :) 2. "dma map ops " I have no idea what it is used for? I have grep the src, and it seems only x86 implement it. appreciate your help, miloody -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
