On 2014/11/20 15:40, Arnd Bergmann wrote: > 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 > ok, I think the your reply to catalin is clear, I got it, add a appropriate mask for the dev is reasonable, I think it should be fixed later.
But in my case, if I don't use the DMA_CMA, the dma_alloc_coherent should use the swiotlb directly which maximum is 16M, so unless I use the kmalloc otherwise I have no better idea for that. Regards Ding > . > -- 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/
