Subject: Re: [net-next PATCH v2 11/15] dt-bindings: net: dsa: qca8k: Document qca,sgmii-enable-pll

From: Andrew Lunn <[email-masked]>
Date: Sat, 9 Oct 2021 19:13:58 +0200

On Fri, Oct 08, 2021 at 02:22:21AM +0200, Ansuel Smith wrote:
> Document qca,sgmii-enable-pll binding used in the CPU nodes to
> enable SGMII PLL on MAC config.
> 
> Signed-off-by: Ansuel Smith <[email-masked]>
> ---
>  Documentation/devicetree/bindings/net/dsa/qca8k.txt | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/dsa/qca8k.txt b/Documentation/devicetree/bindings/net/dsa/qca8k.txt
> index 208ee5bc1bbb..b9cccb657373 100644
> --- a/Documentation/devicetree/bindings/net/dsa/qca8k.txt
> +++ b/Documentation/devicetree/bindings/net/dsa/qca8k.txt
> @@ -50,6 +50,12 @@ A CPU port node has the following optional node:
>                            managed entity. See
>                            Documentation/devicetree/bindings/net/fixed-link.txt
>                            for details.
> +- qca,sgmii-enable-pll  : For SGMII CPU port, explicitly enable PLL, TX and RX
> +                          chain along with Signal Detection.
> +                          This should NOT be enabled for qca8327.

So how about -EINVAL for qca8327, and document it is not valid then.

> +                          This can be required for qca8337 switch with revision 2.

Maybe add a warning if enabled with revision < 2? I would not make it
an error, because there could be devices manufactured with a mixture
or v1 and v2 silicon. Do you have any idea how wide spread v1 is?

> +                          With CPU port set to sgmii and qca8337 it is advised
> +                          to set this unless a communication problem is observed.

  Andrew