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

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Date:   Fri, 11 Aug 2017 16:39:57 +0530
From:   Arvind Yadav <arvind.yadav.cs@...il.com>
To:     Yong Wu <yong.wu@...iatek.com>, Joerg Roedel <joro@...tes.org>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Robin Murphy <robin.murphy@....com>
Cc:     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

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
>   	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