netdev - Re: [PATCH net-next v7 1/6] dt-bindings: net: Add tx and rx internal delays

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Date:   Thu, 18 Jun 2020 04:01:01 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Dan Murphy <dmurphy@...com>
Cc:     f.fainelli@...il.com, hkallweit1@...il.com, davem@...emloft.net,
        robh@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH net-next v7 1/6] dt-bindings: net: Add tx and rx internal
 delays

On Wed, Jun 17, 2020 at 01:20:14PM -0500, Dan Murphy wrote:
> tx-internal-delays and rx-internal-delays are a common setting for RGMII
> capable devices.
> 
> These properties are used when the phy-mode or phy-controller is set to
> rgmii-id, rgmii-rxid or rgmii-txid.  These modes indicate to the
> controller that the PHY will add the internal delay for the connection.
> 
> Signed-off-by: Dan Murphy <dmurphy@...com>
> ---
>  .../devicetree/bindings/net/ethernet-phy.yaml         | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> index 9b1f1147ca36..b2887476fe6a 100644
> --- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> +++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
> @@ -162,6 +162,17 @@ properties:
>      description:
>        Specifies a reference to a node representing a SFP cage.
>  
> +
> +  rx-internal-delay-ps:
> +    description: |
> +      RGMII Receive PHY Clock Delay defined in pico seconds.  This is used for
> +      PHY's that have configurable RX internal delays.
> +
> +  tx-internal-delay-ps:
> +    description: |
> +      RGMII Transmit PHY Clock Delay defined in pico seconds.  This is used for
> +      PHY's that have configurable TX internal delays.
> +

So in a later patch you have:

default: 2000

That seems to apply that these values only apply when the phy mode
indicates a delay is needed. It would be good to document that here,
when each of these properties will be used. Also, that they default to
2000 when not present.

     Andrew