[Query] doubt on parameters passed to dma_map_single_attrs() API

[Sodagudi Prasad]

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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