linux-kernel - Re: [PATCH 4/5] ARC: AXS103: DTS: Set cpu frequency explicitly via dts

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Date:   Wed, 23 Aug 2017 11:24:15 +0000
From:   Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
To:     Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 4/5] ARC: AXS103: DTS: Set cpu frequency explicitly via
 dts

On Tue, 2017-08-22 at 14:40 -0700, Vineet Gupta wrote:
> On 08/14/2017 09:12 AM, Eugeniy Paltsev wrote:
> > Set cpu frequency explicitly via "cpu-freq" param in cpu 0 node
> > in device tree.
> > 
> > We add "cpu-freq" only to cpu 0 as all cpus are clocking from same
> > clock source (same pll in our case).
> > 
> > We override cpus node in skeleton as we don't need this change for
> > nsim.
> 
> Given that you added a generic feature as part of 1/5 - do other
> platforms 
> abilis/nps need corresponding fixups as this one !

Actually no.
If cpu 0 node don't have "cpu-freq" property we simply print cpu
frequency and don't try to change it.
So we can left other dts untouched. 

> > 
> > Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
> > ---
> >   arch/arc/boot/dts/axc003.dtsi     | 13 +++++++++++++
> >   arch/arc/boot/dts/axc003_idu.dtsi | 35
> > +++++++++++++++++++++++++++++++++++
> >   2 files changed, 48 insertions(+)
> > 
> > diff --git a/arch/arc/boot/dts/axc003.dtsi
> > b/arch/arc/boot/dts/axc003.dtsi
> > index dca7e39..7c7411c 100644
> > --- a/arch/arc/boot/dts/axc003.dtsi
> > +++ b/arch/arc/boot/dts/axc003.dtsi
> > @@ -17,6 +17,19 @@
> >   	#address-cells = <2>;
> >   	#size-cells = <2>;
> >   
> > +	cpus {
> > +		#address-cells = <1>;
> > +		#size-cells = <0>;
> > +
> > +		cpu@0 {
> > +			device_type = "cpu";
> > +			compatible = "snps,archs38";
> > +			reg = <0>;
> > +			cpu-freq = <100000000>;
> > +			clocks = <&core_clk>;
> > +		};
> > +	};
> > +
> >   	cpu_card {
> >   		compatible = "simple-bus";
> >   		#address-cells = <1>;
> > diff --git a/arch/arc/boot/dts/axc003_idu.dtsi
> > b/arch/arc/boot/dts/axc003_idu.dtsi
> > index 5b56bef..44bc01e 100644
> > --- a/arch/arc/boot/dts/axc003_idu.dtsi
> > +++ b/arch/arc/boot/dts/axc003_idu.dtsi
> > @@ -17,6 +17,41 @@
> >   	#address-cells = <2>;
> >   	#size-cells = <2>;
> >   
> > +	cpus {
> > +		#address-cells = <1>;
> > +		#size-cells = <0>;
> > +
> > +		/*
> > +		 * "cpu-freq" was added only to cpu 0 as all cpus
> > are clocking
> > +		 * from same clock source (same pll (core_clk) in
> > our case).
> > +		 */
> > +		cpu@0 {
> > +			device_type = "cpu";
> > +			compatible = "snps,archs38";
> > +			reg = <0>;
> > +			cpu-freq = <100000000>;
> > +			clocks = <&core_clk>;
> > +		};
> > +		cpu@1 {
> > +			device_type = "cpu";
> > +			compatible = "snps,archs38";
> > +			reg = <1>;
> > +			clocks = <&core_clk>;
> > +		};
> > +		cpu@2 {
> > +			device_type = "cpu";
> > +			compatible = "snps,archs38";
> > +			reg = <2>;
> > +			clocks = <&core_clk>;
> > +		};
> > +		cpu@3 {
> > +			device_type = "cpu";
> > +			compatible = "snps,archs38";
> > +			reg = <3>;
> > +			clocks = <&core_clk>;
> > +		};
> > +	};
> > +
> >   	cpu_card {
> >   		compatible = "simple-bus";
> >   		#address-cells = <1>;
> 
> 
-- 
 Eugeniy Paltsev