On Wed, 28 Jul 2010 17:58:50 -0700 (PDT) stepanm@xxxxxxxxxxxxxx wrote: > >> These are just SMMU APIs, and the DMA-mapping API is one layer above > >> this. > >> > >> We have our own SMMU API for the MSM SoCs because we have muliple > >> IOMMUs, > >> each one having multiple contexts, or even having multiple instances of > >> the same context. Our usage model is also quite a bit different from how > >> the DMA APIs are set up. I believe only two IOMMU drivers actually make > >> use of the DMA API (Intel and AMD) and the other ones (OMAP and other > >> SoCs) have their own APIs for their specific use cases. > > > > The DMA API is extremely flexible, it works just fine with all the > > IOMMUs that I've seen so far. Please take a look at > > include/asm-generic/dma-mapping-common.h and its users to see how > > to use multiple IOMMUs depending on the device. > > > > If the OMAP developers got this wrong, that's not your problem :-) > > > > Arnd > > Hi Arnd, > > From what I have been able to tell, the IOMMU interface was written by > AMD/Intel to allow the kvm code to work with a common IOMMU interface. To Don't confuse the IOMMU interface with the DMA API that Arnd mentioned. They are not related at all. The DMA API is defined in Documentation/DMA-API.txt. Arnd told you that include/asm-generic/dma-mapping-common.h is the library to support the DMA API with multiple IOMMUs. Lots of architectures (x86, powerpc, sh, alpha, ia64, microblaze, sparc) use it. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
