Re: [PATCH net-next v3 1/1] net: phy: clear link parameters on admin link down

[Andrew Lunn]

On Wed, Sep 17, 2025 at 11:47:51AM +0200, Oleksij Rempel wrote:
> When a PHY is halted (e.g. `ip link set dev lan2 down`), several
> fields in struct phy_device may still reflect the last active
> connection. This leads to ethtool showing stale values even though
> the link is down.
> 
> Reset selected fields in _phy_state_machine() when transitioning
> to PHY_HALTED and the link was previously up:
> 
> - speed/duplex -> UNKNOWN, but only in autoneg mode (in forced mode
>   these fields carry configuration, not status)
> - master_slave_state -> UNKNOWN if previously supported
> - mdix -> INVALID (state only, same meaning as "unknown")
> - lp_advertising -> always cleared
> 
> The cleanup is skipped if the PHY is in PHY_ERROR state, so the
> last values remain available for diagnostics.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>

Reviewed-by: Andrew Lunn <andrew@xxxxxxx>

    Andrew