linux-kernel - Re: [PATCH v3 2/4] dt-bindings: arm: mediatek: Add new bindings of MediaTek frequency hopping

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Date:   Fri, 30 Sep 2022 14:07:03 -0500
From:   Rob Herring <robh@...nel.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     Johnson Wang <johnson.wang@...iatek.com>,
        krzysztof.kozlowski+dt@...aro.org, sboyd@...nel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com,
        kuan-hsin.lee@...iatek.com, yu-chang.wang@...iatek.com,
        Edward-JW Yang <edward-jw.yang@...iatek.com>
Subject: Re: [PATCH v3 2/4] dt-bindings: arm: mediatek: Add new bindings of
 MediaTek frequency hopping

On Thu, Sep 29, 2022 at 03:07:49PM +0200, AngeloGioacchino Del Regno wrote:
> Il 29/09/22 13:46, Johnson Wang ha scritto:
> > Add the new binding documentation for MediaTek frequency hopping
> > and spread spectrum clocking control.
> > 
> > Co-developed-by: Edward-JW Yang <edward-jw.yang@...iatek.com>
> > Signed-off-by: Edward-JW Yang <edward-jw.yang@...iatek.com>
> > Signed-off-by: Johnson Wang <johnson.wang@...iatek.com>
> > ---
> >   .../arm/mediatek/mediatek,mt8186-fhctl.yaml   | 53 +++++++++++++++++++
> >   1 file changed, 53 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/arm/mediatek/mediatek,mt8186-fhctl.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mt8186-fhctl.yaml b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mt8186-fhctl.yaml
> > new file mode 100644
> > index 000000000000..258dff7ce6bc
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mt8186-fhctl.yaml
> > @@ -0,0 +1,53 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/arm/mediatek/mediatek,mt8186-fhctl.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: MediaTek frequency hopping and spread spectrum clocking control
> > +
> > +maintainers:
> > +  - Edward-JW Yang <edward-jw.yang@...iatek.com>
> > +
> > +description: |
> > +  Frequency hopping control (FHCTL) is a piece of hardware that control
> > +  some PLLs to adopt "hopping" mechanism to adjust their frequency.
> > +  Spread spectrum clocking (SSC) is another function provided by this hardware.
> > +
> > +properties:
> > +  compatible:
> > +    const: mediatek,mt8186-fhctl
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    description: Phandles of the PLL with FHCTL hardware capability.
> > +    minItems: 1
> > +    maxItems: 30
> > +
> > +  mediatek,hopping-ssc-percent:
> > +    description: The percentage of spread spectrum clocking for one PLL.
> > +    minItems: 1
> > +    maxItems: 30
> > +    items:
> > +      default: 0
> > +      minimum: 0
> > +      maximum: 8
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - clocks
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/mt8186-clk.h>
> > +    fhctl: fhctl@...0ce00 {
> > +        compatible = "mediatek,mt8186-fhctl";
> > +        reg = <0x1000c000 0xe00>;
> > +        clocks = <&apmixedsys CLK_APMIXED_MSDCPLL>;
> > +        mediatek,hopping-ssc-percent = <3>;
> > +    };
> 
> 
> .... a more realistic example:

One or 2 cells is really outside the scope of the binding as either is 
valid. If the parent bus only has 32-bits of address space, there's 
little reason to use 2 cells.

> 
>     #include <dt-bindings/clock/mt8186-clk.h>
> 
>     soc {
>         #address-cells = <2>;
>         #size-cells = <2>;
> 
>         fhctl: fhctl@...0ce00 {
>             compatible = "mediatek,mt8186-fhctl";
>             reg = <0 0x1000c000 0 0xe00>;
>             clocks = <&apmixedsys CLK_APMIXED_MSDCPLL>;
>             mediatek,hopping-ssc-percent = <3>;
>         };
>     };
> 
> After which...
> 
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>