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

[Doug Berger]

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