On Fri, 22 May 2009 16:07:32 +0200 Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Friday 22 May 2009, FUJITA Tomonori wrote: > > I don't think that this works for all architectures because a returned > > buffer of alloc_pages_node might not be DMA-capable. Needs to use the > > coherent_dma_mask here. See x86's dma_alloc_coherent and Alpha's > > pci-noop.c (there might be other examples). > > Right, Grant also made the same comment. > > > I think that having a generic header for simple mapping functions > > (dma_map_single, dma_map_page, dma_map_sg, etc) would be useful but > > I'm not sure if we can't have a generic version of > > dma_alloc_coherent. > > > > There are lots of architectures that do > > architecture-specific things. For example, you replaced avr32 > > dma-mapping.h except for dma_alloc_coherent, which seems to be can't > > be generic. > > I agree that it won't be fully generic, because all architectures > with non-coherent DMA will have to do architecture specific setup > to get uncached mappings here. I believe that it can be generic > enough to support all architectures that have a cache-coherent PCI > bus, hence the #ifdef CONFIG_DMA_COHERENT around this function. I'm not sure. And only mips internally uses CONFIG_DMA_COHERENT. The reason why many architectures need architecture-specific alloc_coherent() is not about coherent or not. I like a new helper header file having only generic functions without any ifdef. > E.g. cris could use a one-line redirect to > asm-generic/dma-mapping-linear.h if it did not have the > special dma_get_cache_alignment function. I still would > like to find a better way to handle this one than to > redefine the function. > > > BTW, it looks odd to add dma_debug to dma_map_single, etc but not > > dma_alloc_coherent. ;) > > hehe, sure. I copied the dma_debug stuff from sh, the comments > from avr32 and the dma_alloc_coherent implementation from powerpc, > so I missed this one. > > Thanks for the review. > > Arnd <>< > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
