linux-kernel - Re: [RFC net-next 6/8] net: phylink: Configure MAC/PCS when link is up without PHY

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Date:   Mon, 27 Jan 2020 14:08:34 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Jose Abreu <Jose.Abreu@...opsys.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC net-next 6/8] net: phylink: Configure MAC/PCS when link is
 up without PHY

On Mon, Jan 27, 2020 at 03:00:38PM +0100, Andrew Lunn wrote:
> > Yes, I realise that, but it comes with the expense of potentially
> > breaking mvneta and mvpp2, where the settings are automatically
> > passed between the PCS and MAC in hardware. I also believe DSA
> > works around this, and I need to look at that.
> 
> Hi Russell
> 
> The mv88e6xxx driver has code for when SGMII is used. It transfers the
> negotiated speed from the PCS to the MAC.
> 
> But it recently turned out something like this is also needed for
> other link modes involving the SERDES. It used to work, i think
> because Phylink would initially configure the MAC approximately right,
> or the mv88e6xxx driver was looking at phylink state it should not.
> But it no longer works.

Can you give a hint which platform this is and how to reproduce it
please?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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