net: phy: dp83867: increase SGMII autoneg timer duration

After reset SGMII Autoneg timer is set to 2us (bits 6 and 5 are 01).
That is not enough to finalize autonegatiation on some devices.
Increase this timer duration to maximum supported 16ms.
Signed-off-by: Max Uvarov <muvarov@gmail.com>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/dp83867.c

@@ -26,6 +26,12 @@
 
 /* Extended Registers */
 #define DP83867_CFG4            0x0031
+#define DP83867_CFG4_SGMII_ANEG_MASK (BIT(5) | BIT(6))
+#define DP83867_CFG4_SGMII_ANEG_TIMER_11MS   (3 << 5)
+#define DP83867_CFG4_SGMII_ANEG_TIMER_800US  (2 << 5)
+#define DP83867_CFG4_SGMII_ANEG_TIMER_2US    (1 << 5)
+#define DP83867_CFG4_SGMII_ANEG_TIMER_16MS   (0 << 5)
+
 #define DP83867_RGMIICTL	0x0032
 #define DP83867_STRAP_STS1	0x006E
 #define DP83867_RGMIIDCTL	0x0086
@@ -292,6 +298,18 @@ static int dp83867_config_init(struct phy_device *phydev)
 				     0);
 		if (ret)
 			return ret;
+
+		/* After reset SGMII Autoneg timer is set to 2us (bits 6 and 5
+		 * are 01). That is not enough to finalize autoneg on some
+		 * devices. Increase this timer duration to maximum 16ms.
+		 */
+		ret = phy_modify_mmd(phydev, DP83867_DEVADDR,
+				     DP83867_CFG4,
+				     DP83867_CFG4_SGMII_ANEG_MASK,
+				     DP83867_CFG4_SGMII_ANEG_TIMER_16MS);
+
+		if (ret)
+			return ret;
 	}
 
 	/* Enable Interrupt output INT_OE in CFG3 register */