linux-kernel - Re: [PATCH 2/2] dt-bindings: mediatek: mt8195: add clock property to sound node

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Message-ID: <dc7a1e56248fa58f184568e1ce4504a9233209e2.camel@mediatek.com>
Date:   Fri, 17 Dec 2021 15:35:20 +0800
From:   Trevor Wu <trevor.wu@...iatek.com>
To:     Rob Herring <robh@...nel.org>
CC:     <broonie@...nel.org>, <tiwai@...e.com>, <matthias.bgg@...il.com>,
        <alsa-devel@...a-project.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <jiaxin.yu@...iatek.com>, <shumingf@...ltek.com>
Subject: Re: [PATCH 2/2] dt-bindings: mediatek: mt8195: add clock property
 to sound node

On Thu, 2021-12-16 at 13:06 -0600, Rob Herring wrote:
> On Wed, Dec 15, 2021 at 02:58:35PM +0800, Trevor Wu wrote:
> > clocks and clock-names are added to provide MCLK phandle for sound
> > card.
> > 
> > Signed-off-by: Trevor Wu <trevor.wu@...iatek.com>
> > ---
> >  .../bindings/sound/mt8195-mt6359-rt1011-rt5682.yaml  | 12
> > ++++++++++++
> >  .../bindings/sound/mt8195-mt6359-rt1019-rt5682.yaml  | 12
> > ++++++++++++
> >  2 files changed, 24 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/sound/mt8195-mt6359-
> > rt1011-rt5682.yaml
> > b/Documentation/devicetree/bindings/sound/mt8195-mt6359-rt1011-
> > rt5682.yaml
> > index cf6ad7933e23..b57c856d0cf3 100644
> > --- a/Documentation/devicetree/bindings/sound/mt8195-mt6359-rt1011-
> > rt5682.yaml
> > +++ b/Documentation/devicetree/bindings/sound/mt8195-mt6359-rt1011-
> > rt5682.yaml
> > @@ -32,11 +32,21 @@ properties:
> >      $ref: "/schemas/types.yaml#/definitions/phandle"
> >      description: The phandle of MT8195 HDMI codec node.
> >  
> > +  clocks:
> > +    items:
> > +      - description: phandle and clock specifier for codec MCLK.
> > +
> > +  clock-names:
> > +    items:
> > +      - const: i2so1_mclk
> > +
> >  additionalProperties: false
> >  
> >  required:
> >    - compatible
> >    - mediatek,platform
> > +  - clocks
> > +  - clock-names
> >  
> >  examples:
> >    - |
> > @@ -44,6 +54,8 @@ examples:
> >      sound: mt8195-sound {
> >          compatible = "mediatek,mt8195_mt6359_rt1011_rt5682";
> >          mediatek,platform = <&afe>;
> > +        clocks = <&topckgen 235>; //CLK_TOP_APLL12_DIV2
> > +        clock-names = "i2so1_mclk";
> >          pinctrl-names = "default";
> >          pinctrl-0 = <&aud_pins_default>;
> >      };
> > diff --git a/Documentation/devicetree/bindings/sound/mt8195-mt6359-
> > rt1019-rt5682.yaml
> > b/Documentation/devicetree/bindings/sound/mt8195-mt6359-rt1019-
> > rt5682.yaml
> > index 8f177e02ad35..e4720f76f66b 100644
> > --- a/Documentation/devicetree/bindings/sound/mt8195-mt6359-rt1019-
> > rt5682.yaml
> > +++ b/Documentation/devicetree/bindings/sound/mt8195-mt6359-rt1019-
> > rt5682.yaml
> > @@ -42,11 +42,21 @@ properties:
> >        A list of the desired dai-links in the sound card. Each
> > entry is a
> >        name defined in the machine driver.
> >  
> > +  clocks:
> > +    items:
> > +      - description: phandle and clock specifier for codec MCLK.
> > +
> > +  clock-names:
> > +    items:
> > +      - const: i2so1_mclk
> > +
> >  additionalProperties: false
> >  
> >  required:
> >    - compatible
> >    - mediatek,platform
> > +  - clocks
> > +  - clock-names
> >  
> >  examples:
> >    - |
> > @@ -54,6 +64,8 @@ examples:
> >      sound: mt8195-sound {
> >          compatible = "mediatek,mt8195_mt6359_rt1019_rt5682";
> >          mediatek,platform = <&afe>;
> > +        clocks = <&topckgen 235>; //CLK_TOP_APLL12_DIV2
> > +        clock-names = "i2so1_mclk";
> 
> Being a virtual node, how does it have clocks? This belongs in the
> h/w device that consumes the clock.

Hi Rob,

I also found the same usages in some bindings from nvidia, like[1].

Based on my understanding, it seems not to be recommended now and 
clocks should only be used for a real hw node, is it correct?

If yes, I will try other way to get the clock I need in alsa machine
driver.

[1] 
https://elixir.bootlin.com/linux/v5.16-rc5/source/Documentation/devicetree/bindings/sound/nvidia,tegra-audio-rt5640.txt

Thanks,
Trevor

> >          pinctrl-0 = <&aud_pins_default>;
> >      };
> > -- 
> > 2.18.0
> > 
> >