>> This is called when we submit urb, for OUT data, I think it's
>> sufficient for cache consistency. But what I need to know is how we
>> guarantee the cache consistency for IN data, because the DMA is going
>> to update the physical memory when receiving data from device,
>> something has to be done upon completion of the urb.
>Obviously you looked at map_urb_for_dma. Have you also looked at
unmap_urb_for_dma?
unmap_urb_for_dma -> dma_unmap_single
dma_unmap_single is defined in arch/arm/include/asm/dma-mapping.h as
following
------ snip ------
#ifndef CONFIG_DMABOUNCE
static inline void
dma_unmap_single(struct device *dev, dma_addr_t handle, size_t size,
enum dma_data_direction dir)
{
/* nothing to do */
}
#else
extern void dma_unmap_single(struct device *, dma_addr_t, size_t, enum
dma_data_direction);
#endif
------ snip ------
And CONFIG_DMABOUNCE is not defined in the defconfig.
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