linux-kernel - Re: [PATCH net-next v5 06/12] dt-bindings: net: dsa: lantiq,gswip: add support for MII delay properties

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Message-ID: <20251031002924.GA516142-robh@kernel.org>
Date: Thu, 30 Oct 2025 19:29:24 -0500
From: Rob Herring <robh@...nel.org>
To: Daniel Golle <daniel@...rotopia.org>
Cc: Hauke Mehrtens <hauke@...ke-m.de>, Andrew Lunn <andrew@...n.ch>,
	Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Simon Horman <horms@...nel.org>,
	Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Andreas Schirm <andreas.schirm@...mens.com>,
	Lukas Stockmann <lukas.stockmann@...mens.com>,
	Alexander Sverdlin <alexander.sverdlin@...mens.com>,
	Peter Christen <peter.christen@...mens.com>,
	Avinash Jayaraman <ajayaraman@...linear.com>,
	Bing tao Xu <bxu@...linear.com>, Liang Xu <lxu@...linear.com>,
	Juraj Povazanec <jpovazanec@...linear.com>,
	"Fanni (Fang-Yi) Chan" <fchan@...linear.com>,
	"Benny (Ying-Tsan) Weng" <yweng@...linear.com>,
	"Livia M. Rosu" <lrosu@...linear.com>,
	John Crispin <john@...ozen.org>
Subject: Re: [PATCH net-next v5 06/12] dt-bindings: net: dsa: lantiq,gswip:
 add support for MII delay properties

On Thu, Oct 30, 2025 at 11:28:35AM +0000, Daniel Golle wrote:
> Add support for standard tx-internal-delay-ps and rx-internal-delay-ps
> properties on port nodes to allow fine-tuning of RGMII clock delays.
> 
> The GSWIP switch hardware supports delay values in 500 picosecond
> increments from 0 to 3500 picoseconds, with a post-reset default of 2000
> picoseconds for both TX and RX delays. The driver currently sets the
> delay to 0 in case the PHY is setup to carry out the delay by the
> corresponding interface modes ("rgmii-id", "rgmii-rxid", "rgmii-txid").
> 
> This corresponds to the driver changes that allow adjusting MII delays
> using Device Tree properties instead of relying solely on the PHY
> interface mode.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
> v4:
>  * remove misleading defaults
> 
> v3:
>  * redefine ports node so properties are defined actually apply
>  * RGMII port with 2ps delay is 'rgmii-id' mode
> 
>  .../bindings/net/dsa/lantiq,gswip.yaml        | 31 +++++++++++++++++--
>  1 file changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> index f3154b19af78..8ccbc8942eb3 100644
> --- a/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> +++ b/Documentation/devicetree/bindings/net/dsa/lantiq,gswip.yaml
> @@ -6,8 +6,31 @@ $schema: http://devicetree.org/meta-schemas/core.yaml#
>  
>  title: Lantiq GSWIP Ethernet switches
>  
> -allOf:
> -  - $ref: dsa.yaml#/$defs/ethernet-ports

I think you can keep this as you aren't adding custom properties.

> +$ref: dsa.yaml#
> +
> +patternProperties:
> +  "^(ethernet-)?ports$":
> +    type: object
> +    patternProperties:
> +      "^(ethernet-)?port@[0-6]$":

> +        $ref: dsa-port.yaml#
> +        unevaluatedProperties: false

And drop these lines. You may need 'additionalProperties: true' if the 
tools warn.

> +
> +        properties:
> +          tx-internal-delay-ps:
> +            enum: [0, 500, 1000, 1500, 2000, 2500, 3000, 3500]
> +            description:
> +              RGMII TX Clock Delay defined in pico seconds.
> +              The delay lines adjust the MII clock vs. data timing.
> +              If this property is not present the delay is determined by
> +              the interface mode.
> +          rx-internal-delay-ps:
> +            enum: [0, 500, 1000, 1500, 2000, 2500, 3000, 3500]
> +            description:
> +              RGMII RX Clock Delay defined in pico seconds.
> +              The delay lines adjust the MII clock vs. data timing.
> +              If this property is not present the delay is determined by
> +              the interface mode.
>  
>  maintainers:
>    - Hauke Mehrtens <hauke@...ke-m.de>
> @@ -113,8 +136,10 @@ examples:
>                      port@0 {
>                              reg = <0>;
>                              label = "lan3";
> -                            phy-mode = "rgmii";
> +                            phy-mode = "rgmii-id";
>                              phy-handle = <&phy0>;
> +                            tx-internal-delay-ps = <2000>;
> +                            rx-internal-delay-ps = <2000>;
>                      };
>  
>                      port@1 {
> -- 
> 2.51.2