netdev - Re: Linux network PHY initial configuration for ports not 'up'

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Message-ID: <dccfed75-bf35-49fc-b949-1067f4d7e794@lunn.ch>
Date: Wed, 9 Oct 2024 02:30:51 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Tim Harvey <tharvey@...eworks.com>
Cc: Florian Fainelli <f.fainelli@...il.com>,
	netdev <netdev@...r.kernel.org>
Subject: Re: Linux network PHY initial configuration for ports not 'up'

> So you are thinking the right place to address this is in boot
> firmware and the network switch init there should go and disable all
> PHY's by default then? I'm good with that approach and can code that
> up.

I've seen some use cases where the link should be up as fast as
possible. If you force the link down until it is configured up, you
can be adding a little over 1 second delay for autoneg to
complete. I've even see cases there u-boot kicks off autoneg, before
jumping into Linux so that by the time Linux userspace is running and
admin up the interface, autoneg has completed and the link is usable.

There are diverse requirements here and any changes somebody wants to
make is likely to cause a regression for somebody.

	Andrew