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: <33198e39-8c86-85db-76c2-c5ce18dee290@gmail.com>
Date:   Tue, 21 Feb 2023 11:53:43 -0800
From:   Doug Berger <opendmb@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
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 2/21/2023 11:41 AM, Andrew Lunn wrote:
> 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]
> 
I am, though I was not aware of their addition to ethtool and I avoided 
referencing them by name out of an overabundance of political 
correctness ;).

Thanks for bringing this to my attention.

> The broadcom PHYs call genphy_config_aneg() -> __genphy_config_aneg()
> -> genphy_setup_master_slave() which should configure this, even when
> auto-neg is off.
Yes, this sounds good. Perhaps Xiaolei is not setting these properly 
when forcing 1000.

> 
> 	 Andrew
Thanks again!
     Doug