linux-kernel - Re: [PATCH 2/5] clk: qcom: apcs-msm8916: get parent clock names from DT

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Date:   Mon, 09 Sep 2019 09:17:03 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     "Jorge Ramirez-Ortiz, Linaro" <jorge.ramirez-ortiz@...aro.org>
Cc:     agross@...nel.org, jorge.ramirez-ortiz@...aro.org,
        mturquette@...libre.com, bjorn.andersson@...aro.org,
        niklas.cassel@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] clk: qcom: apcs-msm8916: get parent clock names from DT

Quoting Jorge Ramirez-Ortiz, Linaro (2019-09-09 07:17:40)
> On 09/09/19 03:21:16, Stephen Boyd wrote:
> > Quoting Jorge Ramirez-Ortiz (2019-08-26 09:45:07)
> > > @@ -76,10 +88,11 @@ static int qcom_apcs_msm8916_clk_probe(struct platform_device *pdev)
> > >         a53cc->src_shift = 8;
> > >         a53cc->parent_map = gpll0_a53cc_map;
> > >  
> > > -       a53cc->pclk = devm_clk_get(parent, NULL);
> > > +       a53cc->pclk = of_clk_get(parent->of_node, pll_index);
> > 
> > Presumably the PLL was always index 0, so why are we changing it to
> > index 1 sometimes? Seems unnecessary.
> > 
> 
> it came as a personal preference. hope it is acceptable (I would
> rather not change it)
> 
> apcs-msm8916.c declares the following
> 
> [..]
> static const u32 gpll0_a53cc_map[] = { 4, 5 };
> static const char *gpll0_a53cc[] = {
>        "gpll0_vote",
>         "a53pll",
>         };
> [..]
> 
> 
> now will be doing this
> 
> --- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> @@ -429,7 +429,8 @@
>      compatible = "qcom,msm8916-apcs-kpss-global", "syscon";
>      reg = <0xb011000 0x1000>;
>      #mbox-cells = <1>;
> -                   clocks = <&a53pll>;
> +                 clocks = <&gcc GPLL0_VOTE>, <&a53pll>;
> +                 clock-names = "aux", "pll";
>                       #clock-cells = <0>;
>                };
>                                                                                                                 
> 
> so I chose to keep the consistency between the clocks definition and
> just change the index before calling of_clk_get.
> 

But now the binding is different for the same compatible. I'd prefer we
keep using devm_clk_get() and use a device pointer here and reorder the
map and parent arrays instead. The clocks property shouldn't change in a
way that isn't "additive" so that we maintain backwards compatibility.