Messages in this thread | | | Date | Tue, 22 Mar 2016 15:53:02 +0530 | From | Sodagudi Prasad <> | Subject | [Query] doubt on parameters passed to dma_map_single_attrs() API |
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Hi All,
Would like to check whether the dma_map_single_attrs() API, can accept ptr variable from high memory or not? If we pass the memory pointer, which is pointing high memory does not work with virt_to_page API.
10 static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr, 11 size_t size, 12 enum dma_data_direction dir, 13 struct dma_attrs *attrs) 14 { 15 const struct dma_map_ops *ops = get_dma_ops(dev); 16 dma_addr_t addr; 17 18 kmemcheck_mark_initialized(ptr, size); 19 BUG_ON(!valid_dma_direction(dir)); 20 addr = ops->map_page(dev, virt_to_page(ptr), 21 (unsigned long)ptr & ~PAGE_MASK, size, 22 dir, attrs); <Prasad> using the virt_to_page for the high memory will end up with wrong address. 23 debug_dma_map_page(dev, virt_to_page(ptr), 24 (unsigned long)ptr & ~PAGE_MASK, size, 25 dir, addr, true); 26 return addr; 27 }
The only restriction which is observed that, ptr should point to physically contiguous memory.
So can we pass high memory mapped address to dma_map_single API or not?
-Thanks, Prasad
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