On Wed, 17 Jun 2009 10:18:45 +1000 Benjamin Herrenschmidt <b...@kernel.crashing.org> wrote:
> On Tue, 2009-06-16 at 20:02 +0200, Arnd Bergmann wrote: > > On Tuesday 16 June 2009, Scott Wood wrote: > > > > 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? > > > > Ah, yes you are right. PowerPC implements dma_alloc_noncoherent as > > dma_alloc_coherent, so dma_cache_sync() is actually a NOP (or should be). > > But we still need to sync the result of dma_map_* when used multiple > times for a single mapping. We have dma_sync_{single|sg}_for_{cpu|device} API for the above purpose. dma_cache_sync is supposed to be used only with the buffers that dma_alloc_noncoherent() returns. On architecutures that maps dma_alloc_noncoherent to dma_alloc_coherent, dma_cache_sync() is supposed to be NOP. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev