[PATCH 5/8] powerpc: override dma_get_required_mask by platform hook and ops

[Benjamin Herrenschmidt]

On Wed, 2011-05-11 at 15:25 -0700, Nishanth Aravamudan wrote:
> From: Milton Miller <miltonm at bga.com>
> 
> The hook dma_get_required_mask is supposed to return the mask required
> by the platform to operate efficently.  The generic version of
> dma_get_required_mask in driver/base/platform.c returns a mask based
> only on max_pfn.  However, this is likely too big for iommu systems
> and could be too small for platforms that require a dma offset or have
> a secondary window at a high offset.

The result of those 3 patches doesn't build on top of my current tree,
the generic dma_ops lacks the dma_get_required_mask hook. I'll have a
look again after the merge window.

Cheers,
Ben.