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

[Paul Brook <paul@codesourcery.com>]

> 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.

Paul