Loongson's code is derived from octeon. So, I also don't know whether mb() is really needed. Huacai On Sun, Dec 31, 2017 at 12:09 AM, Christoph Hellwig <hch@xxxxxx> wrote: > Hi David and others, > > I've recently been refactoring the dma direct mapping and swiotlb > code, and one odd thing I noticed is that the octeon and loongson > swiotlb ops have mb() calls after basically all swiotlb calls. > > None of that is explained in either the earlier octeon dma map > commits, nor the commit that added the octeon swiotlb support > (b93b2abce497873be97d765b848e0a955d29f200), and neither in the > loonsoon commit that apparently copy and pasted it > (1299b0e05e106f621fff1504df5251f2a678097e). > > Can someone explain what these memory barrier are supposed to do? >
