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From:   Enric Balletbo Serra <eballetbo@gmail.com>
Date:   Mon, 31 May 2021 23:36:07 +0200
Message-ID: <CAFqH_53nNca8VG=09djYseJBWWg5j=YFTfPjxJL5w-aTyBmCng@mail.gmail.com>
Subject: Re: [PATCH 2/3] soc: mtk-pm-domains: do not register smi node as syscon
To:     Hsin-Yi Wang <hsinyi@chromium.org>
Cc:     Matthias Brugger <matthias.bgg@gmail.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        chun-jie.chen@mediatek.corp-partner.google.com,
        Yong Wu <yong.wu@mediatek.com>
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Hi Hsin-Yi,

(again without html, sorry for the noise)

Thank you for the patch.

Missatge de Hsin-Yi Wang <hsinyi@chromium.org> del dia dl., 31 de maig
2021 a les 6:35:
>
> Mediatek requires mmsys clocks to be unprepared during suspend,
> otherwise system has chances to hang.
>
> syscon_regmap_lookup_by_phandle_optional() will attach and prepare the
> first clock in smi node, leading to additional prepare to the clock
> which is not balanced with the prepare/unprepare pair in resume/suspend
> callbacks.
>
> If a power domain node requests an smi node and the smi node's first
> clock is an mmsys clock, it will results in an unstabke suspend resume.

Typo s/unstabke/unstable/

I think it would be nice to have a Fixes tag for that patch. So can be
picked for the stable kernel more easily.

>
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>

I have a nit below but the patch looks good to me. So

Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

> ---
>  drivers/soc/mediatek/mtk-pm-domains.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/soc/mediatek/mtk-pm-domains.c b/drivers/soc/mediatek/mtk-pm-domains.c
> index 536d8c64b2b4..a9ba71eee4bb 100644
> --- a/drivers/soc/mediatek/mtk-pm-domains.c
> +++ b/drivers/soc/mediatek/mtk-pm-domains.c
> @@ -296,7 +296,7 @@ generic_pm_domain *scpsys_add_one_domain(struct scpsys *scpsys, struct device_no
>  {
>         const struct scpsys_domain_data *domain_data;
>         struct scpsys_domain *pd;
> -       struct device_node *root_node = scpsys->dev->of_node;
> +       struct device_node *root_node = scpsys->dev->of_node, *smi_node;

nit: Personal preference, but I'd prefer to add the smi_node in a new
line, so it's really clear that the only thing you are doing here is
adding a new variable.

>         struct property *prop;
>         const char *clk_name;
>         int i, ret, num_clks;
> @@ -352,9 +352,13 @@ generic_pm_domain *scpsys_add_one_domain(struct scpsys *scpsys, struct device_no
>         if (IS_ERR(pd->infracfg))
>                 return ERR_CAST(pd->infracfg);
>
> -       pd->smi = syscon_regmap_lookup_by_phandle_optional(node, "mediatek,smi");
> -       if (IS_ERR(pd->smi))
> -               return ERR_CAST(pd->smi);
> +       smi_node = of_parse_phandle(node, "mediatek,smi", 0);
> +       if (smi_node) {
> +               pd->smi = device_node_to_regmap(smi_node);
> +               of_node_put(smi_node);
> +               if (IS_ERR(pd->smi))
> +                       return ERR_CAST(pd->smi);
> +       }
>
>         num_clks = of_clk_get_parent_count(node);
>         if (num_clks > 0) {
> --
> 2.32.0.rc0.204.g9fa02ecfa5-goog
>
>
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