From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Subject: Re: [PATCHv3 06/19] iommu/tegra: smmu: Select ARM_DMA_USE_IOMMU in
	Kconfig
Date: Fri, 01 Nov 2013 10:55:41 -0600
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To: Hiroshi Doyu <hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Cc: "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" <iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
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On 10/31/2013 02:16 AM, Hiroshi Doyu wrote:
> Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> wrote @ Wed, 30 Oct 2013 23:15:00 +0100:
> 
>> On 10/18/2013 04:26 AM, Hiroshi Doyu wrote:
>>> SMMU expects ARM_DMA_USE_IOMMU to be enabled to use DMA mapping API by
>>> default.
>>
>> Is the select required for the driver to be useful at all (in which case
>> it's fine), or simply for things to work "better" (define "better"), in
>> which case perhaps leaving it optional is more correct.
> 
> Practically DMA API is the only interface for IOMMU(ARM_DMA_USE_IOMMU)
> for us, but technically they are/should be independent.

I would be tempted to deal with this in the defconfig, but I suppose
handling it as a Kconfig select is fine too; there's probably no real
disadvantage in doing so.