Re: [Linaro-mm-sig] [RFC] ARM DMA mapping TODO, v1

On Thu, Apr 21, 2011 at 09:29:16PM +0200, Arnd Bergmann wrote:

4. Implement an architecture independent version of dma_map_ops based on the iommu.h API. As Joerg mentioned, this has been missing for some time, and it would be better to do it once than for each IOMMU separately. This is probably a lot of work.

Yes, thats missing for a long time. It will also need some changes to the IOMMU-API but that should be doable. The best would be to extend the IOMMU-API so that it also supports GART-like IOMMUs. This way every dma_ops implementation on all the architectures providing such an IOMMU could be covered with the architecture independent dma_ops implementation. This would only leave the low-level hardware access in the IOMMU drivers. I think this also requires to change the current semantics of the existing IOMMU-API implementations. I will prepare a write-up of my ideas for discussion.

Regards,

Joerg