Commit ccb989e4 authored by Oleksij Rempel's avatar Oleksij Rempel Committed by Jakub Kicinski
Browse files

net: phy: microchip: Reset LAN88xx PHY to ensure clean link state on LAN7800/7850 



Fix outdated MII_LPA data in the LAN88xx PHY, which is used in LAN7800
and LAN7850 USB Ethernet controllers. Due to a hardware limitation, the
PHY cannot reliably update link status after parallel detection when the
link partner does not support auto-negotiation. To mitigate this, add a
PHY reset in `lan88xx_link_change_notify()` when `phydev->state` is
`PHY_NOLINK`, ensuring the PHY starts in a clean state and reports
accurate fixed link parallel detection results.

Fixes: 792aec47 ("add microchip LAN88xx phy driver")
Signed-off-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20241125084050.414352-1-o.rempel@pengutronix.de


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 51ee075d

drivers/net/phy/microchip.c

+21 −0
Original line number Diff line number Diff line
@@ -351,6 +351,22 @@ static int lan88xx_config_aneg(struct phy_device *phydev) 
static void lan88xx_link_change_notify(struct phy_device *phydev)

{

	int temp;

	int ret;



	/* Reset PHY to ensure MII_LPA provides up-to-date information. This

	 * issue is reproducible only after parallel detection, as described

	 * in IEEE 802.3-2022, Section 28.2.3.1 ("Parallel detection function"),

	 * where the link partner does not support auto-negotiation.

	 */

	if (phydev->state == PHY_NOLINK) {

		ret = phy_init_hw(phydev);

		if (ret < 0)

			goto link_change_notify_failed;



		ret = _phy_start_aneg(phydev);

		if (ret < 0)

			goto link_change_notify_failed;

	}



	/* At forced 100 F/H mode, chip may fail to set mode correctly

	 * when cable is switched between long(~50+m) and short one.
@@ -377,6 +393,11 @@ static void lan88xx_link_change_notify(struct phy_device *phydev) 
		temp |= LAN88XX_INT_MASK_MDINTPIN_EN_;

		phy_write(phydev, LAN88XX_INT_MASK, temp);

	}



	return;



link_change_notify_failed:

	phydev_err(phydev, "Link change process failed %pe\n", ERR_PTR(ret));

}



/**