Re: PowerPC PCI DMA issues (prefetch/coherency?)

From: Scott Wood
Date: Tue Jun 16 2009 - 13:49:16 EST

Arnd Bergmann wrote:
On Tuesday 16 June 2009, Scott Wood wrote:
Chris Pringle wrote:
Ah right - that would explain what we're seeing then... Doh. Thought I might have been onto something then. Is there any way to force a cache flush? That'd at least prove it was a caching issue if it resolved the problem.

If the whole system is noncoherent, that is the right solution.

I meant it more as a test than a permanent solution...

If the
device is the only one, you can also use dma_alloc_noncoherent() and
flush explicitly with dma_cache_sync().

I don't see how that would help -- aren't those also controlled by CONFIG_NOT_COHERENT_CACHE?

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