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From:   Nicolas Boichat <drinkcat@chromium.org>
Date:   Thu, 4 Jun 2020 10:29:19 +0800
Message-ID: <CANMq1KBRe81Sa4A6sCM2egOVRWCJbUNPsXHpfzkT33XGVZXBhg@mail.gmail.com>
Subject: Re: [PATCH v15 06/11] soc: mediatek: Add subsys clock control for bus protection
To:     Weiyi Lu <weiyi.lu@mediatek.com>
Cc:     Enric Balletbo Serra <eballetbo@gmail.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Rob Herring <robh@kernel.org>,
        Sascha Hauer <kernel@pengutronix.de>,
        James Liao <jamesjj.liao@mediatek.com>,
        Fan Chen <fan.chen@mediatek.com>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Devicetree List <devicetree@vger.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        srv_heupstream <srv_heupstream@mediatek.com>
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On Thu, May 21, 2020 at 5:06 PM Weiyi Lu <weiyi.lu@mediatek.com> wrote:
>
> For the bus protection operations, some subsys clocks need to be enabled
> before releasing the protection, and vice versa.
> But those subsys clocks could only be controlled once its corresponding
> power domain is turned on first.
> In this patch, we add the subsys clock control into its relevant steps.
>
> Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
> ---
>  drivers/soc/mediatek/mtk-scpsys.c | 62 +++++++++++++++++++++++++++++++++++++--
>  1 file changed, 60 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
> index 59a525a..ef2c668 100644
> --- a/drivers/soc/mediatek/mtk-scpsys.c
> +++ b/drivers/soc/mediatek/mtk-scpsys.c
> [snip]
>         val |= PWR_ISO_BIT;
> @@ -498,6 +511,39 @@ static int scpsys_power_off(struct generic_pm_domain *genpd)
>         return ret;
>  }
>
> +static int init_subsys_clks(struct platform_device *pdev,
> +               const char *prefix, struct clk **clk)
> +{
> +       struct device_node *node = pdev->dev.of_node;
> +       u32 prefix_len, sub_clk_cnt = 0;
> +       struct property *prop;
> +       const char *clk_name;
> +
> +       prefix_len = strlen(prefix);
> +
> +       of_property_for_each_string(node, "clock-names", prop, clk_name) {
> +               if (!strncmp(clk_name, prefix, prefix_len) &&
> +                               (clk_name[prefix_len] == '-')) {
> +                       if (sub_clk_cnt >= MAX_SUBSYS_CLKS) {
> +                               dev_err(&pdev->dev,
> +                                       "subsys clk out of range %d\n",
> +                                       sub_clk_cnt);
> +                               return -EINVAL;
> +                       }
> +
> +                       clk[sub_clk_cnt] = devm_clk_get(&pdev->dev,
> +                                               clk_name);
> +
> +                       if (IS_ERR(clk[sub_clk_cnt]))
> +                               return PTR_ERR(clk[sub_clk_cnt]);
> +
> +                       sub_clk_cnt++;
> +               }
> +       }
> +
> +       return sub_clk_cnt;
> +}
> +
>  static int init_basic_clks(struct platform_device *pdev, struct clk **clk,
>                         const char * const *name)
>  {
> @@ -596,6 +642,18 @@ static struct scp *init_scp(struct platform_device *pdev,
>                 if (ret)
>                         return ERR_PTR(ret);
>
> +               if (data->subsys_clk_prefix) {
> +                       ret = init_subsys_clks(pdev,
> +                                       data->subsys_clk_prefix,
> +                                       scpd->subsys_clk);
> +                       if (ret < 0) {
> +                               dev_err(&pdev->dev,
> +                                       "%s: subsys clk unavailable\n",
> +                                       data->name);

init_subsys_clks should already have printed an error (directly or
indirectly), so this is not needed.

> +                               return ERR_PTR(ret);
> +                       }
> +               }
> +
>                 genpd->name = data->name;
>                 genpd->power_off = scpsys_power_off;
>                 genpd->power_on = scpsys_power_on;
> --
> 1.8.1.1.dirty