On Friday 11 March 2011, Marek Szyprowski wrote: > > > > does not support IOMMUs, but that could be changed by wrapping it > > > > using the include/asm-generic/dma-mapping-common.h infrastructure. > > > > > > ARM dma-mapping framework also requires some additional research for better DMA > > > support (there are still issues with multiple mappings to be resolved). > > > > You mean mapping the same memory into multiple devices, or a different problem? > > Mapping the same memory area multiple times with different cache settings is not > legal on ARMv7+ systems. Currently the problems might caused by the low-memory > kernel linear mapping and second mapping created for example by dma_alloc_coherent() > function. Yes, I know this problem, but I don't think the case you describe is a serious limitation (there are more interesting cases, though): dma_map_single() etc will create additional *bus* addresses for a physical address, not additional virtual addresses. dma_alloc_coherent should allocate memory that is not also mapped cached, which is what I thought we do correctly. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
