Re: provide in-place uncached remapping for dma-direct v2

[Robin Murphy]

On 24/02/2020 7:44 pm, Christoph Hellwig wrote:
> Hi all,
>
> this series provides support for remapping places uncached in-place in
> the generic dma-direct code, and moves openrisc over from its own
> in-place remapping scheme.  The arm64 folks also had interest in such
> a scheme to avoid problems with speculating into cache aliases.
>
> Also all architectures that always use small page mappings for the
> kernel and have non-coherent DMA should look into enabling this
> scheme, as it is much more efficient than the vmap remapping.
>
> Changes since v1:
>   - share the arch hook for inline remap and uncached segment support

For the whole series:

Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>

I think we might ultimately want to fiddle around a bit more in 
dma_direct_alloc_pages() to give ARCH_HAS_DMA_SET_UNCACHED clear 
precedence over DMA_DIRECT_REMAP if they have to coexist, but let's land 
these patches first as a solid foundation.

Thanks,
Robin.