net: phy: enhance GPY115 loopback disable function

GPY115 need reset PHY when it comes out from loopback mode if the firmware
version number (lower 8 bits) is equal to or below 0x76.

Fixes: 7d901a1e87 ("net: phy: add Maxlinear GPY115/21x/24x driver")
Signed-off-by: Xu Liang <lxu@maxlinear.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/mxl-gpy.c

@@ -493,6 +493,25 @@ static int gpy_loopback(struct phy_device *phydev, bool enable)
 	return ret;
 }
 
+static int gpy115_loopback(struct phy_device *phydev, bool enable)
+{
+	int ret;
+	int fw_minor;
+
+	if (enable)
+		return gpy_loopback(phydev, enable);
+
+	ret = phy_read(phydev, PHY_FWV);
+	if (ret < 0)
+		return ret;
+
+	fw_minor = FIELD_GET(PHY_FWV_MINOR_MASK, ret);
+	if (fw_minor > 0x0076)
+		return gpy_loopback(phydev, 0);
+
+	return genphy_soft_reset(phydev);
+}
+
 static struct phy_driver gpy_drivers[] = {
 	{
 		PHY_ID_MATCH_MODEL(PHY_ID_GPY2xx),
@@ -527,7 +546,7 @@ static struct phy_driver gpy_drivers[] = {
 		.handle_interrupt = gpy_handle_interrupt,
 		.set_wol	= gpy_set_wol,
 		.get_wol	= gpy_get_wol,
-		.set_loopback	= gpy_loopback,
+		.set_loopback	= gpy115_loopback,
 	},
 	{
 		PHY_ID_MATCH_MODEL(PHY_ID_GPY115C),
@@ -544,7 +563,7 @@ static struct phy_driver gpy_drivers[] = {
 		.handle_interrupt = gpy_handle_interrupt,
 		.set_wol	= gpy_set_wol,
 		.get_wol	= gpy_get_wol,
-		.set_loopback	= gpy_loopback,
+		.set_loopback	= gpy115_loopback,
 	},
 	{
 		.phy_id		= PHY_ID_GPY211B,