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Date:   Mon, 25 Jan 2021 15:40:42 -0600
From:   Rob Herring <robh@kernel.org>
To:     Amelie Delaunay <amelie.delaunay@foss.st.com>
Cc:     Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-stm32@st-md-mailman.stormreply.com
Subject: Re: [PATCH v2 1/2] dt-bindings: phy: phy-stm32-usbphyc: add
 #clock-cells required property
Message-ID: <20210125214042.GA1049362@robh.at.kernel.org>
References: <20210114171314.18946-1-amelie.delaunay@foss.st.com>
 <20210114171314.18946-2-amelie.delaunay@foss.st.com>
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In-Reply-To: <20210114171314.18946-2-amelie.delaunay@foss.st.com>
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On Thu, Jan 14, 2021 at 06:13:13PM +0100, Amelie Delaunay wrote:
> usbphyc provides a unique clock called ck_usbo_48m.
> STM32 USB OTG needs a 48Mhz clock (utmifs_clk48) for Full-Speed operation.
> ck_usbo_48m is a possible parent clock for USB OTG 48Mhz clock.
> 
> ck_usbo_48m is available as soon as the PLL is enabled.
> 
> Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
> ---
> No change in v2.
> ---
>  .../devicetree/bindings/phy/phy-stm32-usbphyc.yaml          | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml b/Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml
> index 46df6786727a..4e4da64b8e01 100644
> --- a/Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml
> +++ b/Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml
> @@ -51,6 +51,10 @@ properties:
>    vdda1v8-supply:
>      description: regulator providing 1V8 power supply to the PLL block
>  
> +  '#clock-cells':
> +    description: number of clock cells for ck_usbo_48m consumer
> +    const: 0
> +
>  #Required child nodes:
>  
>  patternProperties:
> @@ -102,6 +106,7 @@ required:
>    - "#size-cells"
>    - vdda1v1-supply
>    - vdda1v8-supply
> +  - '#clock-cells'

You can't really make new properties required as it's not backwards 
compatible. If things can never work without or the binding has never 
been used, then you can. You just need to spell this out in the commit 
msg.

>    - usb-phy@0
>    - usb-phy@1
>  
> @@ -120,6 +125,7 @@ examples:
>          vdda1v8-supply = <&reg18>;
>          #address-cells = <1>;
>          #size-cells = <0>;
> +        #clock-cells = <0>;
>  
>          usbphyc_port0: usb-phy@0 {
>              reg = <0>;
> -- 
> 2.17.1
>