net: phy: dp83867: fix speed 10 in sgmii mode

For supporting 10Mps speed in SGMII mode DP83867_10M_SGMII_RATE_ADAPT bit
of DP83867_10M_SGMII_CFG register has to be cleared by software.
That does not affect speeds 100 and 1000 so can be done on init.
Signed-off-by: NMax Uvarov <muvarov@gmail.com>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/dp83867.c

@@ -30,6 +30,8 @@
 #define DP83867_STRAP_STS1	0x006E
 #define DP83867_RGMIIDCTL	0x0086
 #define DP83867_IO_MUX_CFG	0x0170
+#define DP83867_10M_SGMII_CFG   0x016F
+#define DP83867_10M_SGMII_RATE_ADAPT_MASK BIT(7)
 
 #define DP83867_SW_RESET	BIT(15)
 #define DP83867_SW_RESTART	BIT(14)
@@ -277,6 +279,21 @@ static int dp83867_config_init(struct phy_device *phydev)
 				       DP83867_IO_MUX_CFG_IO_IMPEDANCE_CTRL);
 	}
 
+	if (phydev->interface == PHY_INTERFACE_MODE_SGMII) {
+		/* For support SPEED_10 in SGMII mode
+		 * DP83867_10M_SGMII_RATE_ADAPT bit
+		 * has to be cleared by software. That
+		 * does not affect SPEED_100 and
+		 * SPEED_1000.
+		 */
+		ret = phy_modify_mmd(phydev, DP83867_DEVADDR,
+				     DP83867_10M_SGMII_CFG,
+				     DP83867_10M_SGMII_RATE_ADAPT_MASK,
+				     0);
+		if (ret)
+			return ret;
+	}
+
 	/* Enable Interrupt output INT_OE in CFG3 register */
 	if (phy_interrupt_is_valid(phydev)) {
 		val = phy_read(phydev, DP83867_CFG3);