Re: [PATCH 5/6] dmaengine: omap-dma: Remove mapping between virtual channels and requests

[Russell King - ARM Linux]

On Tue, Feb 24, 2015 at 04:21:22PM +0200, Peter Ujfalusi wrote:
> Do not direct map the virtual channels to sDMA request number. When the
> sDMA is behind of a crossbar this direct mapping can cause situations when
> certain channel can not be requested since the crossbar request number
> will no longer match with the sDMA request line.
> The direct mapping for virtual channels with HW request lines will make it
> harder to implement MEM_TO_MEM mode for the driver.

I assume when you talk about MEM_TO_MEM, you're referring to a DMA_MEMCPY
driver.

mem2mem should not be handled by the slave driver.  This should be a
separate DMA engine driver structure which does not have DMA_SLAVE set.

See how amba-pl08x handles this.

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