[RFC PATCH 03/11] ppc: Create ops to choose between direct window and iommu based on device mask

[FUJITA Tomonori]

On Sat, 09 Oct 2010 10:44:53 +1100
Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:

> On Fri, 2010-10-08 at 10:33 -0700, Nishanth Aravamudan wrote:
> > Also allow the coherent ops to be iommu if only the coherent mask is too
> > small, mostly for driver that do not set set the coherent mask but also
> > don't use the coherent api.
> 
> You are doing the transition at map_sg time which is a hot path, I don't
> like that. Also you add all those "choose" variants of the dma ops...
> not very nice at all.

Agreed, looks hacky.


> You may want to look at the patches I posted to the list a while back
> for doing direct DMA on Bimini:
> 
> [PATCH 1/2] powerpc/dma: Add optional platform override of dma_set_mask()

Would it be cleaner if each ppc dma_map_ops has the own set_dma_mask
and dma_set_mask simply calls dma_map_ops->set_dma_mask?


> [PATCH 2/2] powerpc/dart_iommu: Support for 64-bit iommu bypass window on PCIe