linux-kernel - Re: [PATCH v2 12/13] iommu/rockchip: Add runtime PM support

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Date:   Wed, 17 Jan 2018 15:52:49 +0800
From:   JeffyChen <jeffy.chen@...k-chips.com>
To:     Tomasz Figa <tfiga@...omium.org>
CC:     linux-kernel@...r.kernel.org, Ricky Liang <jcliang@...omium.org>,
        Robin Murphy <robin.murphy@....com>,
        simon xue <xxm@...k-chips.com>,
        Heiko Stuebner <heiko@...ech.de>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        "list@....net:IOMMU DRIVERS" <iommu@...ts.linux-foundation.org>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 12/13] iommu/rockchip: Add runtime PM support

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
>
>
>