From mboxrd@z Thu Jan  1 00:00:00 1970
From: jeffy.chen@rock-chips.com (JeffyChen)
Date: Wed, 17 Jan 2018 15:52:49 +0800
Subject: [PATCH v2 12/13] iommu/rockchip: Add runtime PM support
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References: <20180116132540.18939-1-jeffy.chen@rock-chips.com>
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Message-ID: <5A5F00D1.5010506@rock-chips.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi Tomasz,

On 01/17/2018 03:38 PM, Tomasz Figa wrote:
>>> >>Don't we need to check here (and in _shutdown() too) if we have a
>>> >>domain attached?
>> >
>> >hmmm, right, the startup might been called by resume, so should check
>> >iommu->domain here.
>> >
>> >but the shutdown would be called at the end of detach or suspend, it could
>> >be not attached or attached.
> If startup might be called by resume, without domain attached, what
> prevents shutdown from being called by suspend after that resume,
> still without domain attached? Is it guaranteed that if resume is
> called, someone will attach a domain before suspend is called?
>
no, the shutdown would be called by:
1/ end of detach_dev
so it would be not attached at that time

2/ suspend
so it could be attached, and also could be not attached


anyway, i think the shutdown would work without domain attached(just 
disable paging and clear the iommu bases) ;)

> Best regards,
> Tomasz
>
>
>