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From:   Ansuel Smith <ansuelsmth@gmail.com>
To:     Florian Fainelli <f.fainelli@gmail.com>
Cc:     Ansuel Smith <ansuelsmth@gmail.com>, Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Russell King <linux@armlinux.org.uk>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [RFC PATCH net-next v4 20/28] net: dsa: qca8k: clear MASTER_EN after phy read/write
Date:   Sat,  8 May 2021 02:29:10 +0200
Message-Id: <20210508002920.19945-20-ansuelsmth@gmail.com>
In-Reply-To: <20210508002920.19945-1-ansuelsmth@gmail.com>
References: <20210508002920.19945-1-ansuelsmth@gmail.com>
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Clear MDIO_MASTER_EN bit from MDIO_MASTER_CTRL after read/write
operation. The MDIO_MASTER_EN bit is not reset after read/write
operation and the next operation can be wrongly interpreted by the
switch as a mdio operation. This cause a production of wrong/garbage
data from the switch and underfined bheavior. (random port drop,
unplugged port flagged with link up, wrong port speed)
Also on driver remove the MASTER_CTRL can be left set and cause the
malfunction of any next driver using the mdio device.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
 drivers/net/dsa/qca8k.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index 0c53b6fdf6ee..2e0d2f918efe 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -661,8 +661,14 @@ qca8k_mdio_write(struct qca8k_priv *priv, int port, u32 regnum, u16 data)
 	if (ret)
 		return ret;
 
-	return qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
-		QCA8K_MDIO_MASTER_BUSY);
+	ret = qca8k_busy_wait(priv, QCA8K_MDIO_MASTER_CTRL,
+			      QCA8K_MDIO_MASTER_BUSY);
+
+	/* even if the busy_wait timeouts try to clear the MASTER_EN */
+	qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
+			QCA8K_MDIO_MASTER_EN);
+
+	return ret;
 }
 
 static int
@@ -697,6 +703,10 @@ qca8k_mdio_read(struct qca8k_priv *priv, int port, u32 regnum)
 
 	val &= QCA8K_MDIO_MASTER_DATA_MASK;
 
+	/* even if the busy_wait timeouts try to clear the MASTER_EN */
+	qca8k_reg_clear(priv, QCA8K_MDIO_MASTER_CTRL,
+			QCA8K_MDIO_MASTER_EN);
+
 	return val;
 }
 
-- 
2.30.2