On Thu, Oct 07, 2021 at 10:50:10AM -0700, Jacob Pan wrote: > On platforms that are DMA snooped, this barrier is not needed. But I think > your point is that once we convert to DMA API, the sync/barrier is covered > by DMA APIs if !dev_is_dma_coherent(dev). Then all archs are good.
No.. my point is that a CPU store release is not necessary a DMA visiable event on all platforms and things like dma_wmb/rmb() may still be necessary. This all needs to be architected before anyone starts writing drivers that assume a coherent DMA model without using a coherent DMA allocation. Jason _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
