netdev - Re: BCM54220: After the BCM54220 closes the auto-negotiation, the configuration forces the 1000M network port to be linked down all the time.

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Message-ID: <Y/UehVXRNHuRprAv@lunn.ch>
Date:   Tue, 21 Feb 2023 20:41:57 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Doug Berger <opendmb@...il.com>
Cc:     "Wang, Xiaolei" <Xiaolei.Wang@...driver.com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "bcm-kernel-feedback-list@...adcom.com" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "richardcochran@...il.com" <richardcochran@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: BCM54220: After the BCM54220 closes the auto-negotiation, the
 configuration forces the 1000M network port to be linked down all the time.

On Tue, Feb 21, 2023 at 10:44:44AM -0800, Doug Berger wrote:
> On 2/17/2023 12:06 AM, Wang, Xiaolei wrote:
> > hi
> > 
> >      When I use the nxp-imx7 board, eth0 is connected to the PC, eth0 is turned off the auto-negotiation mode, and the configuration is forced to 10M, 100M, 1000M. When configured to force 1000M，
> >      The link status of phy status reg(0x1) is always 0, and the chip of phy is BCM54220, but I did not find the relevant datasheet on BCM official website, does anyone have any suggestions or the datasheet of BCM54220?
> > 
> > thanks
> > xiaolei
> > 
> It is my understanding that the 1000BASE-T PHY requires peers to take on
> asymmetric roles and that establishment of these roles requires negotiation
> which occurs during auto-negotiation. Some PHYs may allow manual programming
> of these roles, but it is not standardized and tools like ethtool do not
> support manual specification of such details.

Are you talking about ethtool -s [master-slave|preferred-master|preferred-slave|forced-master|forced-slave]

The broadcom PHYs call genphy_config_aneg() -> __genphy_config_aneg()
-> genphy_setup_master_slave() which should configure this, even when
auto-neg is off.

	 Andrew