net: phy: dp83867: Extend RX strap quirk for SGMII mode

When RX strap in HW is not set to MODE 3 or 4, bit 7 and 8 in CF4
register should be set. The former is already handled in
dp83867_config_init; add the latter in SGMII specific initialization.

Fixes: 2a10154a ("net: phy: dp83867: Add TI dp83867 phy")
Signed-off-by: Harini Katakam <harini.katakam@amd.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/dp83867.c

@@ -853,6 +853,14 @@ static int dp83867_config_init(struct phy_device *phydev)
 		else
 			val &= ~DP83867_SGMII_TYPE;
 		phy_write_mmd(phydev, DP83867_DEVADDR, DP83867_SGMIICTL, val);
+
+		/* This is a SW workaround for link instability if RX_CTRL is
+		 * not strapped to mode 3 or 4 in HW. This is required for SGMII
+		 * in addition to clearing bit 7, handled above.
+		 */
+		if (dp83867->rxctrl_strap_quirk)
+			phy_set_bits_mmd(phydev, DP83867_DEVADDR, DP83867_CFG4,
+					 BIT(8));
 	}
 
 	val = phy_read(phydev, DP83867_CFG3);