net: phy: micrel: Fix the KSZ9131 MDI-X status issue

The MDIX status is not accurately reflecting the current state after the link
partner has manually altered its MDIX configuration while operating in forced
mode.

Access information about Auto mdix completion and pair selection from the
KSZ9131's Auto/MDI/MDI-X status register

Fixes: b64e6a8 ("net: phy: micrel: Add PHY Auto/MDI/MDI-X set driver for KSZ9131")
Signed-off-by: Raju Lakkaraju <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Raju Lakkaraju

drivers/net/phy/micrel.c

@@ -1389,6 +1389,8 @@ static int ksz9131_config_init(struct phy_device *phydev)
 	const struct device *dev_walker;
 	int ret;
 
+	phydev->mdix_ctrl = ETH_TP_MDI_AUTO;
+
 	dev_walker = &phydev->mdio.dev;
 	do {
 		of_node = dev_walker->of_node;
@@ -1438,28 +1440,30 @@ static int ksz9131_config_init(struct phy_device *phydev)
 #define MII_KSZ9131_AUTO_MDIX		0x1C
 #define MII_KSZ9131_AUTO_MDI_SET	BIT(7)
 #define MII_KSZ9131_AUTO_MDIX_SWAP_OFF	BIT(6)
+#define MII_KSZ9131_DIG_AXAN_STS	0x14
+#define MII_KSZ9131_DIG_AXAN_STS_LINK_DET	BIT(14)
+#define MII_KSZ9131_DIG_AXAN_STS_A_SELECT	BIT(12)
 
 static int ksz9131_mdix_update(struct phy_device *phydev)
 {
 	int ret;
 
-	ret = phy_read(phydev, MII_KSZ9131_AUTO_MDIX);
-	if (ret < 0)
-		return ret;
-
-	if (ret & MII_KSZ9131_AUTO_MDIX_SWAP_OFF) {
-		if (ret & MII_KSZ9131_AUTO_MDI_SET)
-			phydev->mdix_ctrl = ETH_TP_MDI;
-		else
-			phydev->mdix_ctrl = ETH_TP_MDI_X;
+	if (phydev->mdix_ctrl != ETH_TP_MDI_AUTO) {
+		phydev->mdix = phydev->mdix_ctrl;
 	} else {
-		phydev->mdix_ctrl = ETH_TP_MDI_AUTO;
-	}
+		ret = phy_read(phydev, MII_KSZ9131_DIG_AXAN_STS);
+		if (ret < 0)
+			return ret;
 
-	if (ret & MII_KSZ9131_AUTO_MDI_SET)
-		phydev->mdix = ETH_TP_MDI;
-	else
-		phydev->mdix = ETH_TP_MDI_X;
+		if (ret & MII_KSZ9131_DIG_AXAN_STS_LINK_DET) {
+			if (ret & MII_KSZ9131_DIG_AXAN_STS_A_SELECT)
+				phydev->mdix = ETH_TP_MDI;
+			else
+				phydev->mdix = ETH_TP_MDI_X;
+		} else {
+			phydev->mdix = ETH_TP_MDI_INVALID;
+		}
+	}
 
 	return 0;
 }