Re: [RFC PATCH v2 2/3] arm64: add IOMMU dma_ops

[Yong Wu <yong.wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>]

On Tue, 2015-02-10 at 12:07 +0000, Robin Murphy wrote:
> On 10/02/15 04:39, Yingjoe Chen wrote:
> > On Fri, 2015-02-06 at 14:55 +0000, Robin Murphy wrote
> > <...>
> >> diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h
> >> index 6932bb5..c1b271f 100644
> >> --- a/arch/arm64/include/asm/dma-mapping.h
> >> +++ b/arch/arm64/include/asm/dma-mapping.h
> >> @@ -62,13 +62,30 @@ static inline bool is_device_dma_coherent(struct device *dev)
> >>
> >>   #include <asm-generic/dma-mapping-common.h>
> >>
> >> +#ifdef CONFIG_IOMMU_DMA
> >> +static inline struct iommu_dma_domain *get_dma_domain(struct device *dev)
> >> +{
> >> +	return dev->archdata.dma_domain;
> >> +}
> >> +
> >> +static inline void set_dma_domain(struct device *dev,
> >> +				  struct iommu_dma_domain *dma_domain)
> >> +{
> >> +	dev->archdata.dma_domain = dma_domain;
> >> +}
> >> +#endif
> >> +
> >>   static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> >>   {
> >> +	if (WARN_ON(dev && get_dma_domain(dev)))
> >> +		return DMA_ERROR_CODE;
> >>   	return (dma_addr_t)paddr;
> >>   }
> >
> >
> > Hi Robin,
> >
> > Build fail if CONFIG_IOMMU_DMA is not enabled.
> >
> > In file included from ../include/linux/dma-mapping.h:82:0,
> >                   from ../arch/arm64/kernel/asm-offsets.c:23:
> > ../arch/arm64/include/asm/dma-mapping.h: In function 'phys_to_dma':
> > ../arch/arm64/include/asm/dma-mapping.h:81:2: error: implicit declaration of function 'get_dma_domain' [-Werror=implicit-function-declaration]
> >    if (WARN_ON(dev && get_dma_domain(dev)))
> >    ^
> >
> > Joe.C
> 
> Bah, how did I manage to make such a half-finished mess of the includes? 
> Current fixup diff below.
> 
> Thanks,
> Robin.
> 
Dear Robin,
     We have test this patch on our mt8173, it also could work well.
Tested-by: Yong Wu <yong.wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>

     And I have 2 questiones about how to use this iommu.
     1)if We call "arch_setup_dma_ops" to create a iommu domain, then is
this function "bus_set_iommu" who also need "struct iommu_ops *"
necessary to be called or not in your design?
     2)int (*domain_init)(struct iommu_domain *domain);
       About this function, it will alloc pagetable for the iommu
domain. And We expect the pagetable memory is uncacheable, so try to
call "dma_alloc_coherent", unfortunately the "struct device *" can't be
passed into this function. so is it possible if adding a parameter in
this function.

 Thanks.