dma-direct: re-enable mmap for !CONFIG_MMU (1fbf57d0) · Commits · 戴 / test

nommu configfs can trivially map the coherent allocations to user space, as no actual page table setup is required and the kernel and the user space programs share the same address space. Fixes: ("dma-mapping: remove CONFIG_ARCH_NO_COHERENT_DMA_MMAP") Signed-off-by:

Christoph Hellwig <hch@lst.de> Reported-by:

dillon min <dillon.minfei@gmail.com> Reviewed-by:

Vladimir Murzin <vladimir.murzin@arm.com> Tested-by:

dillon min <dillon.minfei@gmail.com>

kernel/dma/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -71,6 +71,7 @@ config SWIOTLB
		# in the pagetables
		#
		config DMA_NONCOHERENT_MMAP
		default y if !MMU
		bool

		config DMA_COHERENT_POOL

kernel/dma/direct.c

+0 −14

Original line number	Diff line number	Diff line
		@@ -459,7 +459,6 @@ int dma_direct_get_sgtable(struct device dev, struct sg_table sgt,
		return ret;
		}

		#ifdef CONFIG_MMU
		bool dma_direct_can_mmap(struct device *dev)
		{
		return dev_is_dma_coherent(dev) \|\|
		@@ -485,19 +484,6 @@ int dma_direct_mmap(struct device dev, struct vm_area_struct vma,
		return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
		user_count << PAGE_SHIFT, vma->vm_page_prot);
		}
		#else /* CONFIG_MMU */
		bool dma_direct_can_mmap(struct device *dev)
		{
		return false;
		}

		int dma_direct_mmap(struct device dev, struct vm_area_struct vma,
		void *cpu_addr, dma_addr_t dma_addr, size_t size,
		unsigned long attrs)
		{
		return -ENXIO;
		}
		#endif /* CONFIG_MMU */

		int dma_direct_supported(struct device *dev, u64 mask)
		{

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