Subject: Re: [PATCH v2 02/12] dt-bindings: net: add new property st,ext-phyclk in documentation for stm32

From: Rob Herring <[email-masked]>
Date: Thu, 28 Sep 2023 10:23:01 -0500

On Thu, Sep 28, 2023 at 02:24:17PM +0200, Christophe Roullier wrote:
> Add property st,ext-phyclk to manage cases when PHY have no cristal/quartz
> This property can be used with RMII phy without cristal 50Mhz and when we
> want to select RCC clock instead of ETH_REF_CLK
> Can be used also with RGMII phy with no cristal and we select RCC clock

typo

> instead of ETH_CLK125
> This new property replace st,eth-clk-sel and st,eth-ref-clk-sel

Certainly 1 property is better than 2 for me, but carrying 3 is not 
great. I don't understand why the we need a new property. What can't be 
supported with the existing properties?

> 
> Signed-off-by: Christophe Roullier <[email-masked]>
> ---
>  Documentation/devicetree/bindings/net/stm32-dwmac.yaml | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/stm32-dwmac.yaml b/Documentation/devicetree/bindings/net/stm32-dwmac.yaml
> index ca976281bfc22..54fda8b052abc 100644
> --- a/Documentation/devicetree/bindings/net/stm32-dwmac.yaml
> +++ b/Documentation/devicetree/bindings/net/stm32-dwmac.yaml
> @@ -78,12 +78,21 @@ properties:
>        encompases the glue register, the offset of the control register and
>        the mask to set bitfield in control register
>  
> +  st,ext-phyclk:
> +     description:
> +      set this property in RMII mode when you have PHY without crystal 50MHz and want to
> +      select RCC clock instead of ETH_REF_CLK. or in RGMII mode when you want to select
> +      RCC clock instead of ETH_CLK125.
> +    type: boolean

It's not clear to me what 'external' (assuming that's what 'ext' is 
short for) means. A crystal is external to the PHY too. So it means 'the 
PHY has no crystal'? That's a property of the PHY though, so it should 
be in the PHY's node. If you want this in the MAC node, then name the 
property and make the description primarily about the MAC modes.

> +
>    st,eth-clk-sel:
> +    deprecated: true
>      description:
>        set this property in RGMII PHY when you want to select RCC clock instead of ETH_CLK125.
>      type: boolean
>  
>    st,eth-ref-clk-sel:
> +    deprecated: true
>      description:
>        set this property in RMII mode when you have PHY without crystal 50MHz and want to
>        select RCC clock instead of ETH_REF_CLK.
> -- 
> 2.25.1
>