On Monday 20 June 2011, Marek Szyprowski wrote: > Introduce new alloc/free/mmap methods that take attributes argument. > alloc/free_coherent can be implemented on top of the new alloc/free > calls with NULL attributes. dma_alloc_non_coherent can be implemented > using DMA_ATTR_NONCOHERENT attribute, dma_alloc_writecombine can also > use separate DMA_ATTR_WRITECOMBINE attribute. This way the drivers will > get more generic, platform independent way of allocating dma memory > buffers with specific parameters. > > One more attribute can be usefull: DMA_ATTR_NOKERNELVADDR. Buffers with > such attribute will not have valid kernel virtual address. They might be > usefull for drivers that only exports the DMA buffers to userspace (like > for example V4L2 or ALSA). > > mmap method is introduced to let the drivers create a user space mapping > for a DMA buffer in generic, architecture independent way. > > TODO: update all dma_map_ops clients for all architectures > > Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> Yes, I think that is good, but the change needs to be done atomically across all architectures. This should be easy enough as I believe all other architectures that use dma_map_ops don't even require dma_alloc_noncoherent but just define it to dma_alloc_coherent because they have only coherent memory in regular device drivers. On a related note, do you plan to make the CMA work use this transparently, or do you want to have a DMA_ATTR_LARGE or DMA_ATTR_CONTIGUOUS for CMA? Arnd -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>