Re: [RFC/RFT PATCH 1/2] dma-contiguous: Simplify dma_*_from_contiguous() function calls

[Christoph Hellwig]

On Tue, Apr 30, 2019 at 01:52:26PM +0100, Robin Murphy wrote:
> As Catalin pointed out before, many of the users above may still have 
> implicit assumptions about the default CMA area, i.e. that this won't 
> return something above the limit they originally passed to 
> dma_contiguous_reserve(). I'm not sure how straightforward that is to 
> resolve - at the very least we may have to monkey around with GFP_DMA{32} 
> flags based on where dma_contiguous_default_area lies :(

Or just convert the callers one by one.  The two most interesting ones
are dma-direct which always check addressability after the allocation,
and dma-iommu, which doesn't care.  dma-iommu.c and intel-iommu.c also
don't care, but should use dma-iommu by next merge window anyway,
which leaves arm which is so complicated that we better don't touch
it for now, and xtensa, which I hope to switch to dma-direct in the
next merge window or two.