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. Cheers, Ben. > Actually there seems to be a bug in here: Since dma_alloc_noncoherent > gives you a coherent mapping (or NULL) on noncoherent machines, > dma_cache_sync() is redundant and should not actually flush the > cache, or we should change dma_alloc_noncoherent to do a simple > alloc_pages on CONFIG_NON_COHERENT_CACHE and leave dma_cache_sync() > as it is. > > Arnd <>< > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev