net: phy: micrel: make sure the factory test bit is cleared

The KSZ8081 PHY has a factory test mode which is set at the de-assertion
of the reset line based on the RXER (KSZ8081RNA/RND) or TXC
(KSZ8081MNX/RNB) pin. If a pull-down is missing, or if the pin has a
pull-up, the factory test mode should be cleared by manually writing a 0
(according to the datasheet).
Create another ksz8081_config function to handle this case.

Suggested-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/drivers/net/phy/micrel_ksz8xxx.c b/drivers/net/phy/micrel_ksz8xxx.c
index daa57ce..e27fc45 100644
--- a/drivers/net/phy/micrel_ksz8xxx.c
+++ b/drivers/net/phy/micrel_ksz8xxx.c
@@ -24,6 +24,7 @@
 };
 
 #define MII_KSZPHY_OMSO		0x16
+#define KSZPHY_OMSO_FACTORY_TEST BIT(15)
 #define KSZPHY_OMSO_B_CAST_OFF	(1 << 9)
 
 static int ksz_genconfig_bcastoff(struct phy_device *phydev)
@@ -80,12 +81,30 @@
 	.shutdown = &genphy_shutdown,
 };
 
+static int ksz8081_config(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = phy_read(phydev, MDIO_DEVAD_NONE, MII_KSZPHY_OMSO);
+	if (ret < 0)
+		return ret;
+
+	ret &= ~KSZPHY_OMSO_FACTORY_TEST;
+
+	ret = phy_write(phydev, MDIO_DEVAD_NONE, MII_KSZPHY_OMSO,
+			ret | KSZPHY_OMSO_B_CAST_OFF);
+	if (ret < 0)
+		return ret;
+
+	return genphy_config(phydev);
+}
+
 static struct phy_driver KSZ8081_driver = {
 	.name = "Micrel KSZ8081",
 	.uid = 0x221560,
 	.mask = 0xfffff0,
 	.features = PHY_BASIC_FEATURES,
-	.config = &ksz_genconfig_bcastoff,
+	.config = &ksz8081_config,
 	.startup = &genphy_startup,
 	.shutdown = &genphy_shutdown,
 };