net: phy: microchip: Use genphy_soft_reset() to purge stale LPA bits

JIRA: https://issues.redhat.com/browse/RHEL-75590

commit b4517c3
Author: Oleksij Rempel <o.rempel@pengutronix.de>
Date:   Wed Jul 9 15:07:52 2025 +0200

    net: phy: microchip: Use genphy_soft_reset() to purge stale LPA bits

    Enable .soft_reset for the LAN88xx PHY driver by assigning
    genphy_soft_reset() to ensure that the phylib core performs a proper
    soft reset during reconfiguration.

    Previously, the driver left .soft_reset unimplemented, so calls to
    phy_init_hw() (e.g., from lan88xx_link_change_notify()) did not fully
    reset the PHY. As a result, stale contents in the Link Partner Ability
    (LPA) register could persist, causing the PHY to incorrectly report
    that the link partner advertised autonegotiation even when it did not.

    Using genphy_soft_reset() guarantees a clean reset of the PHY and
    corrects the false autoneg reporting in these scenarios.

    Fixes: ccb989e ("net: phy: microchip: Reset LAN88xx PHY to ensure clean link state on LAN7800/7850")
    Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
    Reviewed-by: Andrew Lunn <andrew@lunn.ch>
    Link: https://patch.msgid.link/20250709130753.3994461-2-o.rempel@pengutronix.de
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Izabela Bakollari <ibakolla@redhat.com>

Author: Izabela Bakollari

drivers/net/phy/microchip.c

@@ -488,6 +488,7 @@ static struct phy_driver microchip_phy_driver[] = {
 	.config_init	= lan88xx_config_init,
 	.config_aneg	= lan88xx_config_aneg,
 	.link_change_notify = lan88xx_link_change_notify,
+	.soft_reset	= genphy_soft_reset,
 
 	/* Interrupt handling is broken, do not define related
 	 * functions to force polling.