[PATCH 2/2] ARM: use cached memory in dma_alloc_coherent() if possible

On Tuesday, 21 December 2010, Russell King - ARM Linux
[off-list ref] wrote:

On Tue, Dec 21, 2010 at 10:20:02AM +0000, Jamie Iles wrote:

quoted

For fully coherent architectures or systems using the ARM ACP to provide
coherency to individual device, use cached memory as the coherent
backing rather than noncached or simply bufferable memory.

As has already been covered by Catalin, as far as we know, no one uses
the ACP yet. ?Do you have a system which does?

I'm not sure there is any publicly available system yet. This may be
present in future systems, though only a few peripherals would
probably be connected to the ACP (like an HD LCD controller). So I
don't think we'll get a completely coherent system and a better
approach may be to add per-device DMA operations.

-- 
Catalin