diff options
| author | Oleksij Rempel <o.rempel@pengutronix.de> | 2025-07-03 13:49:40 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-07-17 18:37:06 +0200 |
| commit | 6fb4cd247cda78e821768d7b18e55c9941633a2e (patch) | |
| tree | 59328971d2470b8d1c148916797a50905f73a0f5 | |
| parent | 850812bd2a157194df4e2655dfe9b0f04a3425f5 (diff) | |
net: phy: smsc: Force predictable MDI-X state on LAN87xx
[ 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>
| -rw-r--r-- | drivers/net/phy/smsc.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c index 871b7d42cdae..09fbc30bfd3d 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; @@ -695,7 +722,7 @@ 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, |