linux-kernel - Re: [PATCH 5/8] iommu/mediatek: Disable iommu clock when system suspend

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Date:   Sat, 12 Aug 2017 17:34:32 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     Arvind Yadav <arvind.yadav.cs@...il.com>
CC:     Joerg Roedel <joro@...tes.org>, Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Robin Murphy <robin.murphy@....com>,
        Will Deacon <will.deacon@....com>,
        Daniel Kurtz <djkurtz@...gle.com>,
        Tomasz Figa <tfiga@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux-foundation.org>, <arnd@...db.de>,
        <honghui.zhang@...iatek.com>, <k.zhang@...iatek.com>,
        <cloud.chou@...iatek.com>, <youlin.pei@...iatek.com>
Subject: Re: [PATCH 5/8] iommu/mediatek: Disable iommu clock when system
 suspend

On Fri, 2017-08-11 at 16:39 +0530, Arvind Yadav wrote:
> Hi Youn,
> 
> 
> On Friday 11 August 2017 03:26 PM, Yong Wu wrote:
> > When system suspend, infra power domain may be off, and the iommu's
> > clock must be disabled when system off, or the iommu's bclk clock maybe
> > disabled after system resume.
> >
> > Signed-off-by: Honghui Zhang <honghui.zhang@...iatek.com>
> > Signed-off-by: Yong Wu <yong.wu@...iatek.com>
> > ---
> >   drivers/iommu/mtk_iommu.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index e81ed9a..b7c8e52 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -675,6 +675,7 @@ static int __maybe_unused mtk_iommu_suspend(struct device *dev)
> >   	reg->ctrl_reg = readl_relaxed(base + REG_MMU_CTRL_REG);
> >   	reg->int_control0 = readl_relaxed(base + REG_MMU_INT_CONTROL0);
> >   	reg->int_main_control = readl_relaxed(base + REG_MMU_INT_MAIN_CONTROL);
> > +	clk_disable_unprepare(data->bclk);
> >   	return 0;
> >   }
> >   
> > @@ -684,6 +685,7 @@ static int __maybe_unused mtk_iommu_resume(struct device *dev)
> >   	struct mtk_iommu_suspend_reg *reg = &data->reg;
> >   	void __iomem *base = data->base;
> >   
> > +	clk_prepare_enable(data->bclk);
> Please handle return value of clk_prepare_enable. It can fail

Thanks for the reminding. I will add it in next version.

> >   	writel_relaxed(reg->standard_axi_mode,
> >   		       base + REG_MMU_STANDARD_AXI_MODE);
> >   	writel_relaxed(reg->dcm_dis, base + REG_MMU_DCM_DIS);
> > @@ -699,7 +701,7 @@ static int __maybe_unused mtk_iommu_resume(struct device *dev)
> >   }
> >   
> >   static const struct dev_pm_ops mtk_iommu_pm_ops = {
> > -	SET_SYSTEM_SLEEP_PM_OPS(mtk_iommu_suspend, mtk_iommu_resume)
> > +	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(mtk_iommu_suspend, mtk_iommu_resume)
> >   };
> >   
> >   static const struct of_device_id mtk_iommu_of_ids[] = {
> ~arvind