From mboxrd@z Thu Jan 1 00:00:00 1970 From: psodagud@codeaurora.org (Sodagudi Prasad) Date: Tue, 22 Mar 2016 15:53:02 +0530 Subject: [Query] doubt on parameters passed to dma_map_single_attrs() API Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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); 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 -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, Linux Foundation Collaborative Project