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

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Message-ID: <5b84c81d0d7f71bb83fcbef860433e4704ae5c72.camel@mediatek.com>
Date:   Thu, 6 Oct 2022 11:23:54 +0000
From:   Johnson Wang (王聖鑫) 
        <Johnson.Wang@...iatek.com>
To:     "robh@...nel.org" <robh@...nel.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Kuan-Hsin Lee (李冠新) 
        <Kuan-Hsin.Lee@...iatek.com>,
        "sboyd@...nel.org" <sboyd@...nel.org>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        Yu-Chang Wang (王煜樟) 
        <Yu-Chang.Wang@...iatek.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        Edward-JW Yang (楊哲維) 
        <Edward-JW.Yang@...iatek.com>
Subject: Re: [PATCH v3 2/4] dt-bindings: arm: mediatek: Add new bindings of
 MediaTek frequency hopping

On Fri, 2022-09-30 at 14:07 -0500, Rob Herring wrote:
> 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
> > > +---
> > > +$id: 
> > > https://urldefense.com/v3/__http://devicetree.org/schemas/arm/mediatek/mediatek,mt8186-fhctl.yaml*__;Iw!!CTRNKA9wMg0ARbw!xVt73f8PaQKph8n0ffGHHmQIxdzooUtGr0xDNVqy_6V0vwcs5k-FLrmkB3PZupSu1ciC$
> > >  
> > > +$schema: 
> > > https://urldefense.com/v3/__http://devicetree.org/meta-schemas/core.yaml*__;Iw!!CTRNKA9wMg0ARbw!xVt73f8PaQKph8n0ffGHHmQIxdzooUtGr0xDNVqy_6V0vwcs5k-FLrmkB3PZulXwBACk$
> > >  
> > > +
> > > +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.
> 

Hi Rob,

Thanks for the explanation.

Then I will keep this example the same in the next version.

BRs,
Johnson Wang
> > 
> >     #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>
> >