From: Grant Grundler on
On Tue, Jun 22, 2010 at 03:30:08PM +0900, FUJITA Tomonori wrote:
> > I don't see any harm in letting drivers know whether we can support
> > consistent DMA allocs for a given struct device or not though, even if
> > the micro-optimization is marginal at best.
> I'm happier with exporting less DMA APIs to drivers because looks like
> new original ways to use the APIs wrongly can be always invented.


> There are architectures that need to turn off the CPU cache for
> coherent memory, I can't find none of them that see if an address is
> coherent or not in dma_is_consistent().

parisc "knows" primarily based on chipset and then checks CPU model.
We hook in the correct dma_ops early in boot before any device drivers
are probed.

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