linux-kernel - Re: [PATCH v3 7/7] clk: qcom: apcs-msm8916: use clk_parent

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Message-ID: <20191220172206.GB1908628@ripper>
Date:   Fri, 20 Dec 2019 09:22:06 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Niklas Cassel <niklas.cassel@...aro.org>,
        linux-arm-msm@...r.kernel.org, amit.kucheria@...aro.org,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 7/7] clk: qcom: apcs-msm8916: use clk_parent_data to
 specify the parent

On Wed 18 Dec 22:23 PST 2019, Stephen Boyd wrote:

> Quoting Niklas Cassel (2019-11-25 05:59:09)
> > diff --git a/drivers/clk/qcom/apcs-msm8916.c b/drivers/clk/qcom/apcs-msm8916.c
> > index 46061b3d230e..bb91644edc00 100644
> > --- a/drivers/clk/qcom/apcs-msm8916.c
> > +++ b/drivers/clk/qcom/apcs-msm8916.c
> > @@ -51,6 +51,19 @@ static int qcom_apcs_msm8916_clk_probe(struct platform_device *pdev)
> >         struct clk_init_data init = { };
> >         int ret = -ENODEV;
> >  
> > +       /*
> > +        * This driver is defined by the devicetree binding
> > +        * Documentation/devicetree/bindings/mailbox/qcom,apcs-kpss-global.txt,
> > +        * however, this driver is registered as a platform device by
> > +        * qcom-apcs-ipc-mailbox.c. Because of this, when this driver
> > +        * uses dev_get_regmap() and devm_clk_get(), it has to send the parent
> > +        * device as argument.
> > +        * When registering with the clock framework, we cannot use this trick,
> > +        * since the clock framework always looks at dev->of_node when it tries
> > +        * to find parent clock names using clk_parent_data.
> > +        */
> > +       dev->of_node = parent->of_node;
> 
> This is odd. The clks could be registered with of_clk_hw_register() but
> then we lose the device provider information. Maybe we should search up
> one level to the parent node and if that has a DT node but the
> clk controller device doesn't we should use that instead?
> 

Yeah, we shouldn't have two struct device with the same of_node in the
system, and your suggestion looks quite reasonable. Do you mind spinning
a patch out of it and we can drop above chunk from Niklas' patch - and
afaict merge all the remaining patches to enable CPR on our first
target!

Thanks,
Bjorn

> ----8<-----
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index b68e200829f2..c8745c415c04 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -3669,7 +3669,7 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
>  	if (dev && pm_runtime_enabled(dev))
>  		core->rpm_enabled = true;
>  	core->dev = dev;
> -	core->of_node = np;
> +	core->of_node = np ? : dev_of_node(dev->parent);
>  	if (dev && dev->driver)
>  		core->owner = dev->driver->owner;
>  	core->hw = hw;