net: phy: smsc: Fix Auto-MDIX configuration when disabled by strap

[ Upstream commit a141af8eb2272ab0f677a7f2653874840bc9b214 ]

Correct the Auto-MDIX configuration to ensure userspace settings are
respected when the feature is disabled by the AUTOMDIX_EN hardware strap.

The LAN9500 PHY allows its default MDI-X mode to be configured via a
hardware strap. If this strap sets the default to "MDI-X off", the
driver was previously unable to enable Auto-MDIX from userspace.

When handling the ETH_TP_MDI_AUTO case, the driver would set the
SPECIAL_CTRL_STS_AMDIX_ENABLE_ bit but neglected to set the required
SPECIAL_CTRL_STS_OVRRD_AMDIX_ bit. Without the override flag, the PHY
falls back to its hardware strap default, ignoring the software request.

This patch corrects the behavior by also setting the override bit when
enabling Auto-MDIX. This ensures that the userspace configuration takes
precedence over the hardware strap, allowing Auto-MDIX to be enabled
correctly in all scenarios.

Fixes: 05b35e7eb9a1 ("smsc95xx: add phylib support")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Andre Edich <andre.edich@microchip.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20250703114941.3243890-2-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
index c88edb19d2e7101a3a7d52e2110f60d03e7c7db6..b7f9c4649652bc2abfac3409aefa8b07ec202457 100644 (file)
--- a/drivers/net/phy/smsc.c
+++ b/drivers/net/phy/smsc.c
@@ -167,7 +167,8 @@ static int lan87xx_config_aneg(struct phy_device *phydev)
                        SPECIAL_CTRL_STS_AMDIX_STATE_;
                break;
        case ETH_TP_MDI_AUTO:
-               val = SPECIAL_CTRL_STS_AMDIX_ENABLE_;
+               val = SPECIAL_CTRL_STS_OVRRD_AMDIX_ |
+                       SPECIAL_CTRL_STS_AMDIX_ENABLE_;
                break;
        default:
                return genphy_config_aneg(phydev);