[RFC 0/3] How to pass IOMMU map attr via DMA API?

Joerg Roedel joro at 8bytes.org
Fri Jun 21 12:03:44 EDT 2013


On Fri, Jun 21, 2013 at 09:17:59AM +0200, Marek Szyprowski wrote:
> Using DMA attributes for this seems to be a bad idea. The dma direction
> parameter is much more appropriate. Will Deacon recently posted a patch
> which does it right, see:
> 
> https://git.linaro.org/gitweb?p=people/mszyprowski/linux-dma-mapping.git;a=commit;h=8fc3749bd31d139db58f874e093255fe62505968

Agreed, that is one usecase the dma-direction parameter was made for. In
particular:

	DMA_FROM_DEVICE		-> Write only mapping
	DMA_TO_DEVICE 		-> Read only mapping
	DMA_BIDIRECTIONAL	-> Read/Write mapping

So no need to use the dma attributes for that.


	Joerg





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