Subject: Re: [PATCH net-next 3/6] net: dsa: add support for retrieving the interface mode

From: "Russell King (Oracle)" <[email-masked]>
Date: Fri, 22 Jul 2022 14:23:18 +0100

On Fri, Jul 22, 2022 at 02:59:36PM +0200, Marek Behún wrote:
>   The 2.5GBASE-X PCS does not support Clause 37 Auto-Negotiation.
>   Hence, the 1000BASE-X PCS is expected to have its Clause 37
>   Auto-Negotiation functionality disabled so that the /C/ ordered set
>   will not be transmitted. If a 2.5GBASE-X PCS receives /C/ ordered
>   set, then undefined behavior may occur.
>   ...

The reason that's probably stated is because there hasn't been any
standardisation of it, different implementations behave differently,
so they can't define a standard behaviour without breaking what's
already out there.

With mvneta, the reality is that the 2.5G speed is implemented by
changing the clock configuration in the COMPHY block (serdes) - which
basically clocks everything 2.5x faster. I seem to remember mvpp2 is
the same deal.

-- 
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