net: phy: dp83867: increase SGMII autoneg timer duration

commit 1a97a477 upstream.

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>
[ adapted for kernels without phy_modify_mmd ]
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/phy/dp83867.c

@@ -33,6 +33,12 @@
 
 /* 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
@@ -311,6 +317,18 @@ static int dp83867_config_init(struct phy_device *phydev)
 
 		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.
+		 */
+		val = phy_read_mmd(phydev, DP83867_DEVADDR, DP83867_CFG4);
+		val &= ~DP83867_CFG4_SGMII_ANEG_MASK;
+		val |= DP83867_CFG4_SGMII_ANEG_TIMER_16MS;
+		ret = phy_write_mmd(phydev, DP83867_DEVADDR, DP83867_CFG4, val);
+
+		if (ret)
+			return ret;
 	}
 
 	/* Enable Interrupt output INT_OE in CFG3 register */