Re: Dmaengine query

From: Linus Walleij
Date: Sun May 23 2010 - 20:01:43 EST

2010/4/19 rd bairva <rbairva@xxxxxxxxx>:

>    My DMA controller supports device to device DMA transfers and we
> need it in some of our drivers. Existing DMA engine framework doesn't
> have support for device to device transfers.
> Do you have any plans for device to device support in DMA engine?
> Can you suggest me some other suggestion for doing this?

Extend the DMA engine with the stuff you need and propose nice
patches, provide them along with a driver that make use of this

What about a signature like this:

struct dma_async_tx_descriptor *(*device_prep_slave2slave)(
struct dma_chan *chan1, struct dma_chan *chan2,
enum dma_data_direction direction,
unsigned long flags);

You'd have to add some semantics comment saying that
DMA_TO_DEVICE means chan1->chan2 and
DMA_FROM_DEVICE means chan1<-chan2.

Could be a bit of hacking but how hard can it be?

Linus Walleij
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