linux-kernel - Re: [RFC net-next 0/2] net: dsa: bcm_sf2: Utilize PHYLINK for all ports

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Message-ID: <20220726112344.3ar7s7khiacqueus@skbuf>
Date:   Tue, 26 Jul 2022 14:23:44 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [RFC net-next 0/2] net: dsa: bcm_sf2: Utilize PHYLINK for all
 ports

Hi Florian,

On Mon, Jul 25, 2022 at 02:49:40PM -0700, Florian Fainelli wrote:
> Hi all,
> 
> Although this should work for all devices, since most DTBs on the
> platforms where bcm_sf2 is use do not populate a 'fixed-link' property
> for their CPU ports, but rely on the Ethernet controller DT node doing
> that, we will not be registering a 'fixed-link' instance for CPU ports.
> 
> This still works because the switch matches the configuration of the
> Ethernet controller, but on BCM4908 where we want to force 2GBits/sec,
> that I cannot test, not so sure.
> 
> So as of now, this series does not produce register for register
> compatile changes.

My understanding of this change set is that it stops overriding the link
status of IMP ports from dsa_switch_ops :: setup (unconditionally) and
it moves it to phylink_mac_link_up(). But the latter may not be called
when you lack a fixed-link, and yet the IMP port(s) still work(s).

This begs the natural question, is overriding the link status ever needed?
It was done since the initial commit for this driver, 246d7f773c13c.