From c40be57e8761317f605df6e4de84b654c2250893 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 22 Apr 2021 13:46:44 +0300
Subject: net: phy: marvell: fix m88e1111_set_downshift

From: Maxim Kochetkov <fido_max@inbox.ru>

[ Upstream commit e7679c55a7249f1315256cfc672d53e84072e223 ]

Changing downshift params without software reset has no effect,
so call genphy_soft_reset() after change downshift params.

As the datasheet says:
Changes to these bits are disruptive to the normal operation therefore,
any changes to these registers must be followed by software reset
to take effect.

Fixes: 5c6bc5199b5d ("net: phy: marvell: add downshift support for M88E1111")
Signed-off-by: Maxim Kochetkov <fido_max@inbox.ru>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/phy/marvell.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
index 04e7b9a7799c..47e5200eb039 100644
--- a/drivers/net/phy/marvell.c
+++ b/drivers/net/phy/marvell.c
@@ -964,22 +964,28 @@ static int m88e1111_get_downshift(struct phy_device *phydev, u8 *data)
 
 static int m88e1111_set_downshift(struct phy_device *phydev, u8 cnt)
 {
-	int val;
+	int val, err;
 
 	if (cnt > MII_M1111_PHY_EXT_CR_DOWNSHIFT_MAX)
 		return -E2BIG;
 
-	if (!cnt)
-		return phy_clear_bits(phydev, MII_M1111_PHY_EXT_CR,
-				      MII_M1111_PHY_EXT_CR_DOWNSHIFT_EN);
+	if (!cnt) {
+		err = phy_clear_bits(phydev, MII_M1111_PHY_EXT_CR,
+				     MII_M1111_PHY_EXT_CR_DOWNSHIFT_EN);
+	} else {
+		val = MII_M1111_PHY_EXT_CR_DOWNSHIFT_EN;
+		val |= FIELD_PREP(MII_M1111_PHY_EXT_CR_DOWNSHIFT_MASK, cnt - 1);
 
-	val = MII_M1111_PHY_EXT_CR_DOWNSHIFT_EN;
-	val |= FIELD_PREP(MII_M1111_PHY_EXT_CR_DOWNSHIFT_MASK, cnt - 1);
+		err = phy_modify(phydev, MII_M1111_PHY_EXT_CR,
+				 MII_M1111_PHY_EXT_CR_DOWNSHIFT_EN |
+				 MII_M1111_PHY_EXT_CR_DOWNSHIFT_MASK,
+				 val);
+	}
 
-	return phy_modify(phydev, MII_M1111_PHY_EXT_CR,
-			  MII_M1111_PHY_EXT_CR_DOWNSHIFT_EN |
-			  MII_M1111_PHY_EXT_CR_DOWNSHIFT_MASK,
-			  val);
+	if (err < 0)
+		return err;
+
+	return genphy_soft_reset(phydev);
 }
 
 static int m88e1111_get_tunable(struct phy_device *phydev,
-- 
2.30.2