net: phy: microchip_t1s: fix reset complete status handling

As per the datasheet DS-LAN8670-1-2-60001573C.pdf, the Reset Complete
status bit in the STS2 register has to be checked before proceeding to
the initial configuration. Reading STS2 register will also clear the
Reset Complete interrupt which is non-maskable.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Parthiban Veerasooran <Parthiban.Veerasooran@microchip.com>
Reviewed-by: Ramón Nordin Rodriguez <ramon.nordin.rodriguez@ferroamp.se>
Tested-by: Ramón Nordin Rodriguez <ramon.nordin.rodriguez@ferroamp.se>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/phy/microchip_t1s.c

@@ -14,6 +14,9 @@
 
 #define LAN867X_REG_IRQ_1_CTL 0x001C
 #define LAN867X_REG_IRQ_2_CTL 0x001D
+#define LAN867X_REG_STS2 0x0019
+
+#define LAN867x_RESET_COMPLETE_STS BIT(11)
 
 /* The arrays below are pulled from the following table from AN1699
  * Access MMD Address Value Mask
@@ -53,6 +56,24 @@ static int lan867x_revb1_config_init(struct phy_device *phydev)
 {
 	int err;
 
+	/* The chip completes a reset in 3us, we might get here earlier than
+	 * that, as an added margin we'll conditionally sleep 5us.
+	 */
+	err = phy_read_mmd(phydev, MDIO_MMD_VEND2, LAN867X_REG_STS2);
+	if (err < 0)
+		return err;
+
+	if (!(err & LAN867x_RESET_COMPLETE_STS)) {
+		udelay(5);
+		err = phy_read_mmd(phydev, MDIO_MMD_VEND2, LAN867X_REG_STS2);
+		if (err < 0)
+			return err;
+		if (!(err & LAN867x_RESET_COMPLETE_STS)) {
+			phydev_err(phydev, "PHY reset failed\n");
+			return -ENODEV;
+		}
+	}
+
 	/* Reference to AN1699
 	 * https://ww1.microchip.com/downloads/aemDocuments/documents/AIS/ProductDocuments/SupportingCollateral/AN-LAN8670-1-2-config-60001699.pdf
 	 * AN1699 says Read, Modify, Write, but the Write is not required if the