Re: [kvm-devel] [Qemu-devel] [PATCH 2/6] PCI DMA API (v2)

[andrzej zaborowski]

On 07/04/2008, Paul Brook <address@hidden> wrote:
> > As a note, the DMA controllers in the ARM system-on-chip's can
>  > byte-swap, do 90deg rotation of 2D arrays, transparency (probably
>  > intened for image blitting, but still available on any kind of
>  > transfers), etc., and most importantly issue interrupts on reaching
>  > different points of a transfer.  It is not worth worrying about them
>  > in this API.  I have been for some time wanting to make a separate api
>  > called soc_dma whose task would be using simply memcpy (or zero-copy)
>  > in the most basic case (interrupts off, no transparency,
>  > same-endianness endpoints), as these properties are common for DMA on
>  > the TI OMAPs, the Intel PXAs and the Samsung S3Cs (which otherwise
>  > have little in common).
>
> Are you sure you aren't confusing the DMA engine itelf (which is just annother
>  peripheral) with a mechanism for allowing dma engines access to the system.

I'm talking about the engine.  I want to add a generic one that will
detect the no-transformation, no-interrupts case and then possibly use
something like IOVector for a whole transfer.