6.15-stable review patch. If anyone has any objections, please let me know.
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From: Oleksij Rempel o.rempel@pengutronix.de
[ Upstream commit 0713e55533c88a20edb53eea6517dc56786a0078 ]
Override the hardware strap configuration for MDI-X mode to ensure a predictable initial state for the driver. The initial mode of the LAN87xx PHY is determined by the AUTOMDIX_EN strap pin, but the driver has no documented way to read its latched status.
This unpredictability means the driver cannot know if the PHY has initialized with Auto-MDIX enabled or disabled, preventing it from providing a reliable interface to the user.
This patch introduces a `config_init` hook that forces the PHY into a known state by explicitly enabling Auto-MDIX.
Fixes: 05b35e7eb9a1 ("smsc95xx: add phylib support") Signed-off-by: Oleksij Rempel o.rempel@pengutronix.de Cc: Andre Edich andre.edich@microchip.com Reviewed-by: Andrew Lunn andrew@lunn.ch Link: https://patch.msgid.link/20250703114941.3243890-3-o.rempel@pengutronix.de Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/phy/smsc.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-)
diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c index adf12d7108b5c..ad9a3d91bb8ae 100644 --- a/drivers/net/phy/smsc.c +++ b/drivers/net/phy/smsc.c @@ -262,6 +262,33 @@ int lan87xx_read_status(struct phy_device *phydev) } EXPORT_SYMBOL_GPL(lan87xx_read_status);
+static int lan87xx_phy_config_init(struct phy_device *phydev) +{ + int rc; + + /* The LAN87xx PHY's initial MDI-X mode is determined by the AUTOMDIX_EN + * hardware strap, but the driver cannot read the strap's status. This + * creates an unpredictable initial state. + * + * To ensure consistent and reliable behavior across all boards, + * override the strap configuration on initialization and force the PHY + * into a known state with Auto-MDIX enabled, which is the expected + * default for modern hardware. + */ + rc = phy_modify(phydev, SPECIAL_CTRL_STS, + SPECIAL_CTRL_STS_OVRRD_AMDIX_ | + SPECIAL_CTRL_STS_AMDIX_ENABLE_ | + SPECIAL_CTRL_STS_AMDIX_STATE_, + SPECIAL_CTRL_STS_OVRRD_AMDIX_ | + SPECIAL_CTRL_STS_AMDIX_ENABLE_); + if (rc < 0) + return rc; + + phydev->mdix_ctrl = ETH_TP_MDI_AUTO; + + return smsc_phy_config_init(phydev); +} + static int lan874x_phy_config_init(struct phy_device *phydev) { u16 val; @@ -696,7 +723,7 @@ static struct phy_driver smsc_phy_driver[] = {
/* basic functions */ .read_status = lan87xx_read_status, - .config_init = smsc_phy_config_init, + .config_init = lan87xx_phy_config_init, .soft_reset = smsc_phy_reset, .config_aneg = lan87xx_config_aneg,