David Xiao wrote: > > However, that won't work with ARMv7's speculative prefetching. I'm > > afraid with such things, DMA direct into userspace mappings becomes a > > _lot_ harder, and lets face it, lots of Linux drivers just aren't going > > to bother supporting this - we can't currently get agreement to have an > > API to map DMA coherent pages into userspace! > > The V7 speculative prefetching will then probably apply to DMA coherency > issue in general, both kernel and user space DMAs. Could this be > addressed by inside the dma_unmap_sg/single() calling dma_cache_maint() > when the direction is DMA_FROM_DEVICE/DMA_BIDIRECTIONAL, to basically > invalidate the related cache lines in case any filled by prefetching? > Assuming dma_unmap_sg/single() is called after each DMA operation is > completed. If it's possible, surely its essential because of O_DIRECT file and block I/O? -- Jamie -- 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
