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

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Date:   Sun, 27 Jun 2021 15:56:12 +0800
From:   Hector Yuan <hector.yuan@...iatek.com>
To:     Rob Herring <robh@...nel.org>
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 Wed, 2021-06-02 at 11:58 -0500, Rob Herring wrote:
> 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.
> 
OK, I will restrict this as 1 in next version.
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - "#performance-domain-cells"
> > +
> > +additionalProperties: true
> 
> Should be false.
> 
OK, thanks
> > +
> > +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