Commit 1d1ddf67 authored Jul 17, 2015 by Robin Murphy Committed by Will Deacon Jul 27, 2015

arm64: dma-mapping: implement dma_get_sgtable()



The default dma_common_get_sgtable() implementation relies on the CPU
address of the buffer being a regular lowmem address. This is not always
the case on arm64, since allocations from the various DMA pools may have
remapped vmalloc addresses, rendering the use of virt_to_page() invalid.

Fix this by providing our own implementation based on the fact that we
can safely derive a physical address from the DMA address in both cases.

CC: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[will: made static]
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent 4b3dc967

arch/arm64/mm/dma-mapping.c

+14 −0

Original line number	Diff line number	Diff line
		@@ -331,10 +331,24 @@ static int __swiotlb_mmap(struct device *dev,
		return ret;
		}

		static int __swiotlb_get_sgtable(struct device dev, struct sg_table sgt,
		void *cpu_addr, dma_addr_t handle, size_t size,
		struct dma_attrs *attrs)
		{
		int ret = sg_alloc_table(sgt, 1, GFP_KERNEL);

		if (!ret)
		sg_set_page(sgt->sgl, phys_to_page(dma_to_phys(dev, handle)),
		PAGE_ALIGN(size), 0);

		return ret;
		}

		static struct dma_map_ops swiotlb_dma_ops = {
		.alloc = __dma_alloc,
		.free = __dma_free,
		.mmap = __swiotlb_mmap,
		.get_sgtable = __swiotlb_get_sgtable,
		.map_page = __swiotlb_map_page,
		.unmap_page = __swiotlb_unmap_page,
		.map_sg = __swiotlb_map_sg_attrs,