netdev - Re: [PATCH v2 2/2] dt-bindings: net: adi,adin: document LP Termination property

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Message-ID: <a30379ee-f746-4923-aaad-4109eaf6f606@lunn.ch>
Date: Tue, 23 Dec 2025 10:33:27 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Osose Itua <osose.itua@...oirfairelinux.com>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, michael.hennerich@...log.com,
	jerome.oufella@...oirfairelinux.com
Subject: Re: [PATCH v2 2/2] dt-bindings: net: adi,adin: document LP
 Termination property

On Mon, Dec 22, 2025 at 05:21:05PM -0500, Osose Itua wrote:
> Add "adi,low-cmode-impedance" boolean property which, when present,
> configures the PHY for the lowest common-mode impedance on the receive
> pair for 100BASE-TX operation.

FYI: The DT Maintainers prefer that binding patches come first in a
patchset.

> diff --git a/Documentation/devicetree/bindings/net/adi,adin.yaml b/Documentation/devicetree/bindings/net/adi,adin.yaml
> index c425a9f1886d..d3c8c5cc4bb1 100644
> --- a/Documentation/devicetree/bindings/net/adi,adin.yaml
> +++ b/Documentation/devicetree/bindings/net/adi,adin.yaml
> @@ -52,6 +52,12 @@ properties:
>      description: Enable 25MHz reference clock output on CLK25_REF pin.
>      type: boolean
>  
> +  adi,low-cmode-impedance:
> +    description: |
> +      Ability to configure for the lowest common-mode impedance on the
> +      receive pair for 100BASE-TX.
> +    type: boolean

You should document that happens if the property is not present. Is
the hardware left alone, so the bootloader might of set it to
something other than reset defaults? Is it forced to the highest
common-mode impedance?

Also, is this an on/off setting? Or are there a range of impedance
values which can be set in the hardware? If it is a range, we might
want to be forward thinking and allow a value in ohms.

	Andrew