linux-kernel - Re: [PATCH v2] clk: qcom: lpasscc: Re-configure the PLL in case lost

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Message-ID: <CAD=FV=WcH0DKhiKp4X8j0mxUUCm-yZmJp1boXqVOhCWeySydiQ@mail.gmail.com>
Date:   Wed, 14 Oct 2020 14:13:50 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-soc@...r.kernel.org>,
        Taniya Das <tdas@...eaurora.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] clk: qcom: lpasscc: Re-configure the PLL in case lost

Hi,

On Wed, Oct 14, 2020 at 10:06 AM Stephen Boyd <sboyd@...nel.org> wrote:
>
> Quoting Douglas Anderson (2020-10-14 08:58:24)
> > diff --git a/drivers/clk/qcom/lpasscorecc-sc7180.c b/drivers/clk/qcom/lpasscorecc-sc7180.c
> > index 228d08f5d26f..ee23eb5b9bf2 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);
>
> Can we use dev_get_remap(dev, NULL) instead?

Good idea.  ...but as far as I can tell there are two regmaps.  I'll use

dev_get_regmap(dev, "lpass_core_cc");


> > +       unsigned int l_val;
> > +       int ret;
> > +
> > +       ret = pm_clk_resume(dev);
> > +       if (ret)
> > +               return ret;
> > +
> > +       /* Read PLL_L_VAL */
>
> Please drop this useless comment. Replace it with something like this
> (if at all):
>
>         /* Reconfigure PLL if PLL was reset across suspend */

We reconfigure more than just the PLL.  I believe that the PLL being
zero is just a clue that we use to know we should re-init the whole
thing.  I've tried to convey this in a comment in the next version.