[PATCH] arm64: dma-mapping: fix dma_to_phys API for IOMMU attached devices

Sinan Kaya okaya at codeaurora.org
Thu Mar 17 09:36:28 PDT 2016

On 3/17/2016 12:14 PM, Arnd Bergmann wrote:
> On Thursday 17 March 2016 12:07:26 Sinan Kaya wrote:
>> On 3/17/2016 11:57 AM, Robin Murphy wrote:
>> Let me know which direction I should go. 
>> 1. Fix phys_to_dma and keep dma_to_phys as in the patch.
>> 2. Remove both of the API from header file, move it to where it is needed. Rename them as swio_phys_to_dma etc.
> Use 2.
> It has been a long way to remove all virt_to_bus/bus_to_virt users
> from the common architectures, we are not putting them back under
> a different name.
> Drivers already know the physical address because that is what they
> put into dma_map_*() in the first place.
> 	Arnd

The first solution that comes to my mind is to implement a weak function in
swiotlb.c with these contents

dma_addr_t __weak swio_phys_to_dma(struct device *dev, phys_addr_t paddr)
        return paddr;

phys_addr_t __weak  swio_dma_to_phys(struct device *dev, dma_addr_t daddr)
        return daddr;

then clean up all the duplicates in dma-mapping.h for all ARCHs that have
identical code. 

For others move the implementation to some source file.

Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

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