# Re: \[v2 1/2\] Docs/devicetree: add serdes-output-amplitude-mv to marvell.txt

- From: Marek Behún \<kabel@kernel.org\>
- Date: 2021-12-02 09:25:53 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/12/11217638
- Thread: https://ratatoskr.run/netdev/2021/12/11217633/t.md

```text
On Thu,  2 Dec 2021 09:05:26 +0100
Holger Brunck [ref] wrote:

> This can be configured from the device tree. Add this property to the
> documentation accordingly. This is a property of the port node, which
> needs to be specified in millivolts
> 
> CC: Andrew Lunn <andrew@lunn.ch>
> CC: Jakub Kicinski <kuba@kernel.org>
> CC: Marek Behún <kabel@kernel.org>
> Signed-off-by: Holger Brunck <redacted>
> ---
>  Documentation/devicetree/bindings/net/dsa/marvell.txt | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/dsa/marvell.txt b/Documentation/devicetree/bindings/net/dsa/marvell.txt
> index 2363b412410c..9292b6f960df 100644
> --- a/Documentation/devicetree/bindings/net/dsa/marvell.txt
> +++ b/Documentation/devicetree/bindings/net/dsa/marvell.txt
> @@ -46,6 +46,11 @@ Optional properties:
>  - mdio?		: Container of PHYs and devices on the external MDIO
>  			  bus. The node must contains a compatible string of
>  			  "marvell,mv88e6xxx-mdio-external"
> +- serdes-output-amplitude-mv: Configure the output amplitude of the serdes
> +			      interface in millivolts. This option can be
> +                              set in the ports node as it is a property of
> +                              the port.
> +    serdes-output-amplitude-mv = <210>;

The suffix should be millivolt, as can be seen in other bindings.

Also I think maybe use "tx" instead of "output"? It is more common to
refere to serdes pairs as rx/tx instead of input/output:

  serdes-tx-amplitude-millivolt

I will probably want to add this property also either to mvneta, or to
A3720 common PHY binding. Andrew, do you think it should be put
somewhere more generic?

Marek
```