linux-kernel - Re: [PATCH v5 3/5] clk: qcom: common: Add interconnect clocks support

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Message-ID: <ZgaceJT2FMsQVoPa@hu-varada-blr.qualcomm.com>
Date: Fri, 29 Mar 2024 16:18:24 +0530
From: Varadarajan Narayanan <quic_varada@...cinc.com>
To: Stephen Boyd <sboyd@...nel.org>
CC: <andersson@...nel.org>, <conor+dt@...nel.org>,
        <devicetree@...r.kernel.org>, <djakov@...nel.org>,
        <dmitry.baryshkov@...aro.org>, <konrad.dybcio@...aro.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <mturquette@...libre.com>,
        <quic_anusha@...cinc.com>, <robh@...nel.org>
Subject: Re: [PATCH v5 3/5] clk: qcom: common: Add interconnect clocks support

On Thu, Mar 28, 2024 at 02:54:52PM -0700, Stephen Boyd wrote:
> Quoting Varadarajan Narayanan (2024-03-28 00:59:34)
> > diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
> > index 75f09e6e057e..9fa271812373 100644
> > --- a/drivers/clk/qcom/common.c
> > +++ b/drivers/clk/qcom/common.c
> > @@ -8,6 +8,8 @@
> >  #include <linux/regmap.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/clk-provider.h>
> > +#include <linux/interconnect-clk.h>
> > +#include <linux/interconnect-provider.h>
>
> Do we need the second include?

Will remove.

> >  #include <linux/reset-controller.h>
> >  #include <linux/of.h>
> >
> > @@ -234,6 +236,41 @@ static struct clk_hw *qcom_cc_clk_hw_get(struct of_phandle_args *clkspec,
> >         return cc->rclks[idx] ? &cc->rclks[idx]->hw : NULL;
> >  }
> >
> > +#if IS_ENABLED(CONFIG_INTERCONNECT_CLK)
> > +static int qcom_cc_icc_register(struct device *dev,
> > +                               const struct qcom_cc_desc *desc)
> > +{
> > +       struct icc_clk_data *icd;
> > +       int i;
> > +
> > +       if (!desc->icc_hws)
> > +               return 0;
> > +
> > +       icd = devm_kcalloc(dev, desc->num_icc_hws, sizeof(*icd), GFP_KERNEL);
> > +       if (!icd)
> > +               return -ENOMEM;
> > +
> > +       for (i = 0; i < desc->num_icc_hws; i++) {
> > +               icd[i].clk = devm_clk_hw_get_clk(dev, desc->icc_hws[i], "qcom");
>
> Make the con_id "icc" instead please, so we know the consumer is
> icc_clk.

Ok.

> Even better would be for the icc_clk device itself to be the
> one requesting with devm_clk_hw_get_clk() so that we associate the clk
> handle with the consumer device. It would also help us make it so that
> drivers defer probe until their clk isn't an orphan.

Not sure if I understand the comments correctly.

In one of the previous patches, had
	icd[i].clk = clks[noc_clks[i]]->hw.clk;

This was said to be error prone since the clock would not be
ref counted. Hence used devm_clk_hw_get_clk before doing
icc_clk_register.

Now, are you suggesting to use the direct clock pointer
and do a devm_clk_hw_get_clk from the consumer driver?
This will take care of the refcounting. However, we will
have to add these clock entries to the consumer DT node.
Is this ok?

> > +               if (IS_ERR(icd[i].clk))
> > +                       return dev_err_probe(dev, PTR_ERR(icd[i].clk),
> > +                                            "get clock failed (%ld)\n",
> > +                                            PTR_ERR(icd[i].clk));
> > +
> > +               icd[i].name = clk_hw_get_name(desc->icc_hws[i]);
> > +       }
> > +
> > +       return PTR_ERR_OR_ZERO(devm_icc_clk_register(dev, desc->first_id,
> > +                                                    desc->num_icc_hws, icd));
> > +}
> > +#else
> > +static int qcom_cc_icc_register(struct device *dev,
> > +                               const struct qcom_cc_desc *desc)
> > +{
> > +       return 0;
> > +}
>
> Instead of this please have an
>
> 	if (!IS_ENABLED(CONFIG_INTERCONNECT_CLK))
> 		return 0;

Ok.

> > +#endif
> > +
> >  int qcom_cc_really_probe(struct platform_device *pdev,
> >                          const struct qcom_cc_desc *desc, struct regmap *regmap)
> >  {
> > @@ -303,7 +340,7 @@ int qcom_cc_really_probe(struct platform_device *pdev,
> >         if (ret)
> >                 return ret;
> >
> > -       return 0;
> > +       return qcom_cc_icc_register(dev, desc);
> >  }
> >  EXPORT_SYMBOL_GPL(qcom_cc_really_probe);
> >
> > diff --git a/drivers/clk/qcom/common.h b/drivers/clk/qcom/common.h
> > index 9c8f7b798d9f..d8ac26d83f3c 100644
> > --- a/drivers/clk/qcom/common.h
> > +++ b/drivers/clk/qcom/common.h
> > @@ -29,6 +29,9 @@ struct qcom_cc_desc {
> >         size_t num_gdscs;
> >         struct clk_hw **clk_hws;
> >         size_t num_clk_hws;
> > +       struct clk_hw **icc_hws;
> > +       size_t num_icc_hws;
> > +       unsigned int first_id;
>
> 'first_id' is gross.

will change it to 'icc_id'.

Thanks
Varada