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From: Arnd Bergmann <arnd@arndb.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Joerg Roedel <jroedel@suse.de>, Joerg Roedel <joro@8bytes.org>,
        linux-arm-kernel@lists.infradead.org, Yong Wu <yong.wu@mediatek.com>,
        iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org,
        Matthias Brugger <matthias.bgg@gmail.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] iommu/mediatek: select ARM_DMA_USE_IOMMU
Date: Mon, 29 Feb 2016 12:29:13 +0100
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On Monday 29 February 2016 11:22:24 Robin Murphy wrote:
> >>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> >>> index b325954cf8f8..ea0998921702 100644
> >>> --- a/drivers/iommu/Kconfig
> >>> +++ b/drivers/iommu/Kconfig
> >>> @@ -341,6 +341,7 @@ config MTK_IOMMU
> >>>     bool "MTK IOMMU Support"
> >>>     depends on ARM || ARM64
> >>>     depends on ARCH_MEDIATEK || COMPILE_TEST
> >>> +   select ARM_DMA_USE_IOMMU
> >>
> >> If going down this route, I'd be inclined to add an "if ARM" there, just
> >> for clarity.
> >
> > That would run into the NEED_SG_DMA_LENGTH problem on other architectures
> > that don't already set it, right?
> 
> Sorry, I'm lost - wouldn't "depends on ARM || ARM64" make other 
> architectures moot? arm64 already has NEED_SG_DMA_LENGTH=y by default.
> 

Nevermind, I didn't notice the dependency on the architecture.

What is keeping us from having 'depends on ARM || ARM64 || COMPILE_TEST'?

I assume it doesn't work yet, but it would be nice to get that done
at some point so we can take advantage of automated build testing like
coverity.

	Arnd