Re: [PATCHv4] DMAEngine: Define interleaved transfer request api

[Vinod Koul]

On Mon, 2011-10-10 at 16:46 +0530, Jassi Brar wrote:
> On 10 October 2011 16:15, Vinod Koul <vinod.koul@xxxxxxxxx> wrote:
> >
> > But I am fine if we find a common ground and merge the two where dmac
> > can cleanly identify direction and mode it is operating.
> >
> The client would set the xfer_direction and dmac would interpret as
> 
> enum xfer_direction {
>      MEM_TO_MEM,   ->  Async/Memcpy mode
>      MEM_TO_DEV,    ->  Slave mode & From Memory to Device
>      DEV_TO_MEM,    ->  Slave mode & From Device to Memory
>      DEV_TO_DEV,     ->  Slave mode & From Device to Device
> }
> 
> How could it get any cleaner?
Consider the case of a dmac driver which supports interleaved dma as
well as memcpy and slave
It needs to interpret dma_data_direction for later cases and
xfer_direction for former ones. Not a clean way to convey same info. And
only reason why we cannot use dma_data_direction here is because we
don't know the "mode", by splitting we overcome that.

-- 
~Vinod

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