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dma-direct: re-enable mmap for !CONFIG_MMU

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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: 62fcee9a3b ("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>
This commit is contained in:
Christoph Hellwig 2020-06-10 10:29:49 +02:00
parent dbed452a07
commit 1fbf57d053
2 changed files with 1 additions and 14 deletions
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1
kernel/dma/Kconfig
View File

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

14
kernel/dma/direct.c
View File

@ -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)
{