linux-kernel - Re: [PATCH] arm64: dma-mapping: fix dma_to

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Message-ID: <56EAD3E2.5070109@arm.com>
Date:	Thu, 17 Mar 2016 15:57:22 +0000
From:	Robin Murphy <robin.murphy@....com>
To:	Sinan Kaya <okaya@...eaurora.org>,
	linux-arm-kernel@...ts.infradead.org, timur@...eaurora.org,
	cov@...eaurora.org, nwatters@...eaurora.org
Cc:	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Max Filippov <jcmvbkbc@...il.com>,
	Joe Perches <joe@...ches.com>,
	"Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>,
	Arnd Bergmann <arnd@...db.de>,
	Jisheng Zhang <jszhang@...vell.com>,
	Dean Nelson <dnelson@...hat.com>,
	"Suzuki K. Poulose" <suzuki.poulose@....com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dma-mapping: fix dma_to_phys API for IOMMU
 attached devices

On 17/03/16 15:50, Sinan Kaya wrote:
> This patch modifies dma_to_phys to call iommu_iova_to_phys to perform dma
> to phys conversions for IOMMU attached devices where dma and physical
> addresses often have distinct values.

What's this for? dma_to_phys() is only used by SWIOTLB, and that's 
mutually exclusive with IOMMU ops.

Also, what about phys_to_dma()?

Robin.

> Signed-off-by: Nate Watterson <nwatters@...eaurora.org>
> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
>   arch/arm64/include/asm/dma-mapping.h |  5 +----
>   arch/arm64/mm/dma-mapping.c          | 16 ++++++++++++++++
>   2 files changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h
> index ba437f0..a0a486c 100644
> --- a/arch/arm64/include/asm/dma-mapping.h
> +++ b/arch/arm64/include/asm/dma-mapping.h
> @@ -69,10 +69,7 @@ static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
>   	return (dma_addr_t)paddr;
>   }
>
> -static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
> -{
> -	return (phys_addr_t)dev_addr;
> -}
> +phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr);
>
>   static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
>   {
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index 331c4ca..8252a92 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -989,3 +989,19 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>   	dev->archdata.dma_coherent = coherent;
>   	__iommu_setup_dma_ops(dev, dma_base, size, iommu);
>   }
> +
> +phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
> +{
> +	phys_addr_t phys = (phys_addr_t)dev_addr;
> +
> +#ifdef CONFIG_IOMMU_DMA
> +	struct iommu_domain *domain;
> +
> +	domain = iommu_get_domain_for_dev(dev);
> +	if (domain)
> +		phys = iommu_iova_to_phys(domain, dev_addr);
> +#endif
> +
> +	return phys;
> +}
> +EXPORT_SYMBOL(dma_to_phys);
>