Hi, James and Christoph, We have modified arch/mips/loongson64/common/dma-swiotlb.c to make Loongson support coherent&non-coherent devices co-exist. You can see code here: https://github.com/linux-loongson/linux-loongson/commit/3f212e36b2432a7c4a843649e4b79c9c0837d1d2 When device is non-coherent, we will call dma_cache_sync(). Then, if dma_cache_sync() is only designed for DMA_ATTR_NON_CONSISTENT, what can I use? 1, __dma_sync_virtual() and __dma_sync() are both static functions, so can't be called in other files. 2, mips_dma_cache_sync() is not static, but I think it isn't designed to be called directly (So it should be static). 3, dma_cache_wback(), dma_cache_inv() and dma_cache_wback_inv() does't take a "direction" argument, so I should determine the direction first (then I will reimplement __dma_cache_sync for myself). So, It seems that I can only use dma_cache_sync(). Huacai On Wed, Jan 24, 2018 at 11:29 PM, Christoph Hellwig <hch@xxxxxx> wrote: > On Wed, Jan 24, 2018 at 03:03:05PM +0000, James Hogan wrote: >> I see, that makes sense. Thanks Christoph. I'll assume this patch isn't >> applicable then unless Huacai adds some explanation. > > In addition there also is no driver that can be used on loongsoon > that actually calls dma_cache_sync either. >
