[PATCH 0/7] DMAENGINE: fixes and PrimeCells

[jassisinghbrar@gmail.com (jassi brar)]

On Fri, May 7, 2010 at 8:43 PM, Linus Walleij
<linus.ml.walleij@gmail.com> wrote:
> 2010/5/7 Russell King - ARM Linux <linux@arm.linux.org.uk>:
>> Or let me put it another way - if people are happy for Linux to support
>> new ARM CPU architectures, but with very little attention given to DMA
>> support on those architectures, then feel free to box the ARM platforms
>> into a corner on DMA support - but on the understanding that _you_ will
>> have to deal with the DMA API breakage on those architectures yourself.
>> Because with ARM platforms not having DMA support, there's absolutely
>> no way to run any checks what so ever on DMA when the CPU architecture
>> support is created.
>
> I'm doing the best I can to meet exactly this goal. The changes done in
> the DMA engine were done towards the end of making the DMA
> engine support *any* DMA controller for the PrimeCells,
with due respect, I think DMA Engine API is very restricting. And it is not
just the 'async' character of it but also some desirable features like
Circular-Linked-Buffer are missing. It may be good enough for Mem->Mem
but is found wanting for Mem<->Dev transfers.
I would like to see some new API defined that address reasonable
requirements of extant platform specific implementations.

> So now I guess I have to make it tick on the block known as PL080/PL081
> as well, and I'll have a try at it.
I always hoped the pl080 core would be segregated out of S3C implementation,
but for some new common DMA API.