6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
[ Upstream commit ccb989e4d1efe0dd81b28c437443532d80d9ecee ]
Fix outdated MII_LPA data in the LAN88xx PHY, which is used in LAN7800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: 792aec47d59d9 ("add microchip LAN88xx phy driver")
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
Link: https://patch.msgid.link/20241125084050.414352-1-o.rempel@xxxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/net/phy/microchip.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/drivers/net/phy/microchip.c b/drivers/net/phy/microchip.c
index d3273bc0da4a1..691969a4910f2 100644
--- a/drivers/net/phy/microchip.c
+++ b/drivers/net/phy/microchip.c
@@ -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));
}
/**
--
2.43.0
