On Thursday 20 November 2014 10:57:53 Ding Tianhong wrote: > On 2014/11/19 16:45, Arnd Bergmann wrote: > > On Wednesday 19 November 2014 11:17:15 Ding Tianhong wrote: > >> On 2014/11/18 2:09, Catalin Marinas wrote: > >>> On Mon, Nov 17, 2014 at 12:18:42PM +0000, Arnd Bergmann wrote: > >> Thanks everyone, I think I found the way to fix it, need to enable > >> DMA_CMA, to reserve a big memory > >> for CMA and set coherent mask for dev, then dma_alloc and dma_mapping will > >> not use the swiotlb until > >> the memory out of mask or swiotlb_force is enabled. > >> > >> If I still understand uncorrectly, please inform me. > >> > > > > Please do not use CMA to work around the problem, but fix the underlying bug > > instead. > > > > The driver should call 'dma_set_mask_and_coherent()' with the appropriate > > dma mask, and check whether that succeeded. However, the code implementing > > dma_set_mask_and_coherent on arm64 also needs to be changed to look up > > the dma-ranges property (see of_dma_configure()), and check if the mask > > is possible. > > > The dma_pfn_offset looks only support arm32, but my platform is aarch64 and I > check the latest kernel version, > I think the dma-rangs still could not work for aarch64, so maybe we should > add dma_pfn_offset for aarch64 first. >
I didn't mean the dma_pfn_offset. The problem is that the of_dma_configure code currently doesn't look at the mask. As I explained in my reply to Catalin, it should set the mask to the size of the dma-ranges if that is 32-bit or smaller, and dma_set_mask should look at the same dma-ranges property to decide what to set the mask to when a driver asks for a mask larger than 64-bit. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/