Re: [PATCH RFC net-next] net: phylink: always config mac for (delayed) phy

[Eric Woudstra <ericwouds@gmail.com>]

On 1/7/25 2:20 PM, Andrew Lunn wrote:
>> I think it is because pl->act_link_an_mode stays at MLO_AN_INBAND, but
>> it needs to be set to MLO_AN_PHY, so that only the phy determines the
>> link state:
>>
>> phylink_resolve() {
>>     ...
>> 	} else if (pl->act_link_an_mode == MLO_AN_PHY) {
>> 		link_state = pl->phy_state;
>>     ...
>> }
> 
> phylink tries to determine the whole chain is up. As Russell says, it
> could be the PCS has not got sync with the PHY for some reason. So
> even if you ignore the PCS state, it might not work. This is actually
> a useful pieces of information. Does the link actually work end to end
> if you only look at the media state? If it does, that would indicate
> the PCS is maybe missing an interrupt, or needs polling for change in
> state.
> 
> 	Andrew

After phylink_mac_initial_config() is re-triggered with the phy
attached, either by the patch, or even with:

ethtool -s eth1 advertise 0x28
(switches to sgmii)
ethtool -s eth1 advertise 0x800000000028
(switches mac back to 2500base-x)

mode is set to MLO_AN_PHY in phylink_pcs_neg_mode() and the link works
end to end.

So the an-mode can be 2 different values, one after link up and another
after these ethtool commands.