On Thu, Sep 21, 2017 at 12:28:25PM +0800, 陈华才 wrote: > Hi, Christoph, > > I have changed dma_get_cache_alignment's return value, and I don't know whether those drivers want to return ARCH_DMA_MINALIGN unconditionally. So I pass a NULL for those drivers, in order to keep their old behavior. Per our documentation yes, they do want ARCH_DMA_MINALIGN. Please Cc all the driver maintainers on your updated patch so that they can review it, though.