linux-kernel - Re: [PATCH 1/2] iommu/mediatek: select ARM_DMA_USE

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Message-ID: <5357325.sBkT8ESvOS@wuerfel>
Date:	Mon, 29 Feb 2016 12:29:13 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Robin Murphy <robin.murphy@....com>
Cc:	Joerg Roedel <jroedel@...e.de>, Joerg Roedel <joro@...tes.org>,
	linux-arm-kernel@...ts.infradead.org,
	Yong Wu <yong.wu@...iatek.com>,
	iommu@...ts.linux-foundation.org,
	linux-mediatek@...ts.infradead.org,
	Matthias Brugger <matthias.bgg@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] iommu/mediatek: select ARM_DMA_USE_IOMMU

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