netdev - [PATCH] net: phy: Fix marvell_set_downshift() from clobbering MSCR register

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Message-Id: <20200311224138.1b98ca46f948789a0eec7ecf@gmail.com>
Date:   Wed, 11 Mar 2020 22:41:38 +0800
From:   Darell Tan <darell.tan@...il.com>
To:     netdev@...r.kernel.org
Cc:     <andrew@...n.ch>, <f.fainelli@...il.com>, <hkallweit1@...il.com>,
        <davem@...emloft.net>
Subject: [PATCH] net: phy: Fix marvell_set_downshift() from clobbering MSCR
 register

Fix marvell_set_downshift() from clobbering MSCR register.

A typo in marvell_set_downshift() clobbers the MSCR register. This
register also shares settings with the auto MDI-X detection, set by
marvell_set_polarity(). In the 1116R init, downshift is set after
polarity, causing the polarity settings to be clobbered.

This bug is present on the 5.4 series and was introduced in commit
6ef05eb73c8f ("net: phy: marvell: Refactor setting downshift into a
helper"). This patch need not be forward-ported to 5.5 because the
functions were rewritten.

Signed-off-by: Darell Tan <darell.tan@...il.com>
---
 drivers/net/phy/marvell.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
index a7796134e..6ab8fe339 100644
--- a/drivers/net/phy/marvell.c
+++ b/drivers/net/phy/marvell.c
@@ -282,7 +282,7 @@ static int marvell_set_downshift(struct phy_device *phydev, bool enable,
 	if (reg < 0)
 		return reg;

-	reg &= MII_M1011_PHY_SRC_DOWNSHIFT_MASK;
+	reg &= ~MII_M1011_PHY_SRC_DOWNSHIFT_MASK;
 	reg |= ((retries - 1) << MII_M1011_PHY_SCR_DOWNSHIFT_SHIFT);
 	if (enable)
 		reg |= MII_M1011_PHY_SCR_DOWNSHIFT_EN;
-- 
2.17.1