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SubjectRe: [PATCH/RFC] dmaengine: add a slave parameter to __dma_request_channel()
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On Thu, 2012-03-08 at 11:16 +0100, Guennadi Liakhovetski wrote:
> I still have the impression, that my specific use-case (sh-mobile), where
> channels can be freely configured for use by _ANY_ client on one of
> _SEVERAL_ DMAC instances, is not fully understood or taken into account.
> For this driver any kind of fixed mapping means, that we'd have to use
> both virtual channels and controllers, adding _a lot_ of complexity to the
> DMAC driver and making the dmaengine core just an "obfuscation layer."
> Yes, I remember Russell proposing core helpers for this. They would help,
> but (1) when would they be available, (2) how well would they be suitable
> for us, (3) they'd take the coding / maintainance burden away, but
> wouldn't reduce complexity and run-time overhead.
Lets try to address you case as well.
On a typical platform
1) how many dma controllers you have?
2) how many clients you have
3) which client can use what controller channel? How is mapping decided,
do you have a mux, is it hard wired by soc designers,....?
Can you pls give a description so that we ensure all models fit in the
final solution?

--
~Vinod



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