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. 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-m68k" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
