Re: [PATCH net-next v2 2/2] net: phy: microchip_t1: Auto-negotiation support for LAN887x

[Andrew Lunn <andrew@lunn.ch>]

On Mon, Dec 16, 2024 at 09:28:30PM +0530, Tarun Alle wrote:
> Adds auto-negotiation support for lan887x T1 phy. After this commit,
> by default auto-negotiation is on and default advertised speed is 1000M.

So i asked about the implications of this. I would of expected
something like:

This will break any system which expects forced behaviour, without
actually configuring forced behaviour both on the local system and
where the link partner is expecting forced configuration, not autoneg.

I think we also need some more details about the autoneg in the commit
message. When used against a standards conforming 100M PHY,
negotiation will fail by default, because this PHY is not conformant
with 100M, or 1G autoneg.

I don't like you are going to cause regressions, especially when you
have decided regressions are worth it for a half broken autoneg.

I actually think it should default to fixed, as it is today. Maybe
with the option to enable the broken autoneg. This is different to all
PHYs we have today, but we try hard to avoid regressions.

What are the plans for this PHY? Will there be a new revision soon
which fixes the broken autoneg? Maybe you should forget about autoneg
for this revision of this PHY, it is too broken, and wait for the next
revision which actually conforms to the standard?

	Andrew