linux-kernel - Re: [PATCH v2 2/3] ARM: dts: exynos: Add assigned clock parent to CMU in Exynos4412 Odroid

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Message-ID: <20200906125640.GB4829@kozik-lap>
Date:   Sun, 6 Sep 2020 14:56:40 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     Rob Herring <robh+dt@...nel.org>, Kukjin Kim <kgene@...nel.org>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sylwester Nawrocki <snawrocki@...nel.org>
Subject: Re: [PATCH v2 2/3] ARM: dts: exynos: Add assigned clock parent to
 CMU in Exynos4412 Odroid

On Fri, Sep 04, 2020 at 09:02:23AM +0200, Marek Szyprowski wrote:
> Hi Krzysztof,
> 
> On 03.09.2020 20:14, Krzysztof Kozlowski wrote:
> > Commit 68605101460e ("ARM: dts: exynos: Add support for audio over HDMI
> > for Odroid X/X2/U3") added assigned clocks under Clock Management Unit.
> >
> > However the dtschema expects "clocks" property if "assigned-clocks" are
> > used.  Add reference to input clock, the parent used in
> > "assigned-clock-parents" to silence the dtschema warnings:
> >
> >    arch/arm/boot/dts/exynos4412-odroidu3.dt.yaml: clock-controller@...30000: 'clocks' is a dependency of 'assigned-clocks'
> >
> > Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> > ---
> >   arch/arm/boot/dts/exynos4412-odroid-common.dtsi | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
> > index ca3c78e0966c..9375df064076 100644
> > --- a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
> > +++ b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
> > @@ -120,6 +120,7 @@
> >   };
> >   
> >   &clock {
> > +	clocks = <&clock CLK_FOUT_EPLL>;
> 
> This should be one of xusbxti or xxti, because this is the proper input 
> clock for the clock controller. However in case of Exynos4, those clocks 
> needs much more cleanup. For the historical reasons, they don't use 
> generic 'fixed-clock' property, but the custom one and they are no 
> instantiated by clock framework, but the exynos4 clock driver...

Indeed, so it would be like:

&clock {
	clocks = <&clock CLK_XUSBXTI>;
};

... or convert the driver to take external clocks while keeping the ABI
(and being bisectable).

Best regards,
Krzysztof


> 
> >   	assigned-clocks = <&clock CLK_FOUT_EPLL>;
> >   	assigned-clock-rates = <45158401>;
> >   };
> 
> Best regards
> -- 
> Marek Szyprowski, PhD
> Samsung R&D Institute Poland
>