linux-kernel - Re: [PATCH v0] clk: qcom: lpasscc: Re-configure the PLL in case lost

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Message-ID: <CAD=FV=XOj-Vg36v8GtE1sjay0jCdCLgRMJtyN9ZYyZhsNkdVfg@mail.gmail.com>
Date:   Tue, 13 Oct 2020 15:26:54 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Taniya Das <tdas@...eaurora.org>
Cc:     Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-soc@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andy Gross <agross@...nel.org>
Subject: Re: [PATCH v0] clk: qcom: lpasscc: Re-configure the PLL in case lost

Hi,

On Tue, Oct 13, 2020 at 11:33 AM Taniya Das <tdas@...eaurora.org> wrote:
>
> In the case where the PLL configuration is lost, then the pm runtime
> resume will reconfigure before usage.
>
> Fixes: edab812d802d ("clk: qcom: lpass: Add support for LPASS clock controller for SC7180")
> Signed-off-by: Taniya Das <tdas@...eaurora.org>
> ---
>  drivers/clk/qcom/lpasscorecc-sc7180.c | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
>
> diff --git a/drivers/clk/qcom/lpasscorecc-sc7180.c b/drivers/clk/qcom/lpasscorecc-sc7180.c
> index 228d08f..5804a93 100644
> --- a/drivers/clk/qcom/lpasscorecc-sc7180.c
> +++ b/drivers/clk/qcom/lpasscorecc-sc7180.c
> @@ -356,6 +356,25 @@ static const struct qcom_cc_desc lpass_audio_hm_sc7180_desc = {
>         .num_gdscs = ARRAY_SIZE(lpass_audio_hm_sc7180_gdscs),
>  };
>
> +static int lpass_core_cc_pm_clk_resume(struct device *dev)
> +{
> +       struct regmap *regmap = dev_get_drvdata(dev);
> +       int l_val;

nit: technically "unsigned int" to match what regmap_read takes.

> +
> +       pm_clk_resume(dev);

Even though pm_clk_resume() doesn't currently return any errors, it
would be good form to check.  AKA:

ret = pm_clk_resume(dev);
if (ret)
  return ret;


> +       /* Read PLL_L_VAL */
> +       regmap_read(regmap, 0x1004, &l_val);
> +       if (!l_val)
> +               clk_fabia_pll_configure(&lpass_lpaaudio_dig_pll, regmap,
> +                               &lpass_lpaaudio_dig_pll_config);
> +       return 0;
> +}
> +
> +static const struct dev_pm_ops lpass_core_pm_ops = {
> +       SET_RUNTIME_PM_OPS(pm_clk_suspend, lpass_core_cc_pm_clk_resume, NULL)
> +};
> +
>  static int lpass_core_cc_sc7180_probe(struct platform_device *pdev)
>  {
>         const struct qcom_cc_desc *desc;
> @@ -386,6 +405,9 @@ static int lpass_core_cc_sc7180_probe(struct platform_device *pdev)
>         clk_fabia_pll_configure(&lpass_lpaaudio_dig_pll, regmap,
>                                 &lpass_lpaaudio_dig_pll_config);
>
> +       pdev->dev.driver->pm = &lpass_core_pm_ops;
> +       dev_set_drvdata(&pdev->dev, regmap);

I'm kinda confused.  Why not just change "lpass_core_cc_pm_ops"?  Then
you can get rid of the above two lines of code and get rid of the
whole "lpass_core_pm_ops" structure?


-Doug