[PATCH net v1 0/4] net: phy: smsc: robustness fixes for LAN87xx/LAN9500

From: Oleksij Rempel
Date: Tue Jul 01 2025 - 08:22:15 EST


Hi all,

The SMSC 10/100 PHYs (LAN87xx family) found in smsc95xx (lan95xx)
USB-Ethernet adapters show several quirks around the Auto-MDIX feature:

- A hardware strap (AUTOMDIX_EN) may boot the PHY in fixed-MDI mode, and
the current driver cannot always override it.

- When Auto-MDIX is left enabled while autonegotiation is forced off,
the PHY endlessly swaps the TX/RX pairs and never links up.

- The driver sets the enable bit for Auto-MDIX but forgets the override
bit, so userspace requests are silently ignored.

- Rapid configuration changes can wedge the link if PHY IRQs are
enabled.

The four patches below make the MDIX state fully predictable and prevent
link failures in every tested strap / autoneg / MDI-X permutation.

Tested on LAN9512 Eval board.

Best Regards,
Oleksij

Oleksij Rempel (4):
net: phy: smsc: Fix Auto-MDIX configuration when disabled by strap
net: phy: smsc: Force predictable MDI-X state on LAN87xx
net: phy: smsc: Fix link failure in forced mode with Auto-MDIX
net: phy: smsc: Disable IRQ support to prevent link state corruption

drivers/net/phy/smsc.c | 61 +++++++++++++++++++++++++++++++++++-------
1 file changed, 52 insertions(+), 9 deletions(-)

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2.39.5