linux-kernel - Re: [RFT PATCH v1 2/4] dt-binding: cpu-topology: Move cpu-map to a common binding.

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Date:   Mon, 3 Dec 2018 16:55:21 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Atish Patra <atish.patra@....com>
Cc:     linux-kernel@...r.kernel.org, Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup@...infault.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        devicetree@...r.kernel.org,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Jeremy Linton <jeremy.linton@....com>,
        Juri Lelli <juri.lelli@....com>,
        "moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-riscv@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Palmer Dabbelt <palmer@...ive.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will.deacon@....com>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [RFT PATCH v1 2/4] dt-binding: cpu-topology: Move cpu-map to a
 common binding.

On Thu, Nov 29, 2018 at 03:28:18PM -0800, Atish Patra wrote:
> cpu-map binding can be used to described cpu topology for both
> RISC-V & ARM. It makes more sense to move the binding to document
> to a common place.
>
> The relevant discussion can be found here.
> https://lkml.org/lkml/2018/11/6/19
>

Looks good to me apart from a minor query below in the example.

Reviewed-by: Sudeep Holla <sudeep.holla@....com>

> Signed-off-by: Atish Patra <atish.patra@....com>
> ---
>  .../{arm/topology.txt => cpu/cpu-topology.txt}     | 81 ++++++++++++++++++----
>  1 file changed, 67 insertions(+), 14 deletions(-)
>  rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (86%)
>
> diff --git a/Documentation/devicetree/bindings/arm/topology.txt b/Documentation/devicetree/bindings/cpu/cpu-topology.txt
> similarity index 86%
> rename from Documentation/devicetree/bindings/arm/topology.txt
> rename to Documentation/devicetree/bindings/cpu/cpu-topology.txt
> index 66848355..1de6fbce 100644
> --- a/Documentation/devicetree/bindings/arm/topology.txt
> +++ b/Documentation/devicetree/bindings/cpu/cpu-topology.txt

[...]

> +Example 3: HiFive Unleashed (RISC-V 64 bit, 4 core system)
> +
> +cpus {
> +	#address-cells = <2>;
> +	#size-cells = <2>;
> +	compatible = "sifive,fu540g", "sifive,fu500";
> +	model = "sifive,hifive-unleashed-a00";
> +
> +	...
> +
> +	cpu-map {
> +		cluster0 {
> +			core0 {
> +				cpu = <&L12>;
> +		 	};
> +			core1 {
> +				cpu = <&L15>;
> +			};
> +			core2 {
> +				cpu0 = <&L18>;
> +			};
> +			core3 {
> +				cpu0 = <&L21>;
> +			};
> +		};
> + 	};
> +
> +	L12: cpu@1 {
> +		device_type = "cpu";
> +		compatible = "sifive,rocket0", "riscv";
> +		reg = <0x1>;
> +	}
> +
> +	L15: cpu@2 {
> +		device_type = "cpu";
> +		compatible = "sifive,rocket0", "riscv";
> +		reg = <0x2>;
> +	}
> +	L18: cpu@3 {
> +		device_type = "cpu";
> +		compatible = "sifive,rocket0", "riscv";
> +		reg = <0x3>;
> +	}
> +	L21: cpu@4 {
> +		device_type = "cpu";
> +		compatible = "sifive,rocket0", "riscv";
> +		reg = <0x4>;
> +	}
> +};

The labels for the CPUs drew my attention. Is it intentionally random
(or even specific) or just chosen to show anything can be used as labels ?
The reason I ask is people tend to copy from existing DT or examples
like here and so want to make sure if it can be kept as generic as
possible in the example. Just my opinion and I am fine if you want to
keep it as is, thought of checking the intentions here.

--
Regards,
Sudeep