linux-kernel - Re: [PATCH v12 2/2] dt-bindings: cpufreq: add bindings for MediaTek cpufreq HW

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Message-ID: <20210602165827.GA3558170@robh.at.kernel.org>
Date:   Wed, 2 Jun 2021 11:58:27 -0500
From:   Rob Herring <robh@...nel.org>
To:     Hector Yuan <hector.yuan@...iatek.com>
Cc:     linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        wsd_upstream@...iatek.com
Subject: Re: [PATCH v12 2/2] dt-bindings: cpufreq: add bindings for MediaTek
 cpufreq HW

On Sun, May 30, 2021 at 12:52:33AM +0800, Hector Yuan wrote:
> From: "Hector.Yuan" <hector.yuan@...iatek.com>
> 
> Add devicetree bindings for MediaTek HW driver.
> 
> Signed-off-by: Hector.Yuan <hector.yuan@...iatek.com>
> ---
>  .../bindings/cpufreq/cpufreq-mediatek-hw.yaml      |   71 ++++++++++++++++++++
>  1 file changed, 71 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> 
> diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> new file mode 100644
> index 0000000..1aa4d54
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> @@ -0,0 +1,71 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/cpufreq/cpufreq-mediatek-hw.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek's CPUFREQ Bindings
> +
> +maintainers:
> +  - Hector Yuan <hector.yuan@...iatek.com>
> +
> +description:
> +  CPUFREQ HW is a hardware engine used by MediaTek
> +  SoCs to manage frequency in hardware. It is capable of controlling frequency
> +  for multiple clusters.
> +
> +properties:
> +  compatible:
> +    const: mediatek,cpufreq-hw
> +
> +  reg:
> +    minItems: 1
> +    maxItems: 2
> +    description: |
> +      Addresses and sizes for the memory of the
> +      HW bases in each frequency domain.
> +
> +  "#performance-domain-cells":
> +    description:
> +      Number of cells in a performance domain specifier. Typically 0 for nodes
> +      representing a single performance domain and 1 for nodes providing
> +      multiple performance domains (e.g. performance controllers), but can be
> +      any value as specified by device tree binding documentation of particular
> +      provider.
> +    enum: [ 0, 1 ]

Can't you restrict this to be 1 for Mediatek h/w? Even if you sometimes 
have a single domain, it's probably more simple for the driver if this 
is fixed.

> +
> +required:
> +  - compatible
> +  - reg
> +  - "#performance-domain-cells"
> +
> +additionalProperties: true

Should be false.

> +
> +examples:
> +  - |
> +    cpus {
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            cpu0: cpu@0 {
> +                device_type = "cpu";
> +                compatible = "arm,cortex-a55";
> +                enable-method = "psci";
> +                performance-domains = <&performance 0>;
> +                reg = <0x000>;
> +            };
> +    };
> +
> +    /* ... */
> +
> +    soc {
> +        #address-cells = <2>;
> +        #size-cells = <2>;
> +
> +        performance: performance-controller@...c00 {
> +            compatible = "mediatek,cpufreq-hw";
> +            reg = <0 0x0011bc10 0 0x120>, <0 0x0011bd30 0 0x120>;
> +
> +            #performance-domain-cells = <1>;
> +        };
> +    };
> -- 
> 1.7.9.5