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From:   Esben Haabendal <esben.haabendal@gmail.com>
To:     netdev@vger.kernel.org
Cc:     Esben Haabendal <eha@deif.com>,
        Richard Cochran <richardcochran@gmail.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH] dp83640: Ensure against premature access to PHY registers after reset
Date:   Fri,  6 Apr 2018 16:05:40 +0200
Message-Id: <20180406140540.13511-1-esben.haabendal@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Esben Haabendal <eha@deif.com>

Signed-off-by: Esben Haabendal <eha@deif.com>
---
 drivers/net/phy/dp83640.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/net/phy/dp83640.c b/drivers/net/phy/dp83640.c
index 654f42d00092..48403170096a 100644
--- a/drivers/net/phy/dp83640.c
+++ b/drivers/net/phy/dp83640.c
@@ -1207,6 +1207,22 @@ static void dp83640_remove(struct phy_device *phydev)
 	kfree(dp83640);
 }
 
+static int dp83640_soft_reset(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = genphy_soft_reset(phydev);
+	if (ret < 0)
+		return ret;
+
+	/* From DP83640 datasheet: "Software driver code must wait 3 us
+	 * following a software reset before allowing further serial MII
+	 * operations with the DP83640." */
+	udelay(3);
+
+	return 0;
+}
+
 static int dp83640_config_init(struct phy_device *phydev)
 {
 	struct dp83640_private *dp83640 = phydev->priv;
@@ -1501,6 +1517,7 @@ static struct phy_driver dp83640_driver = {
 	.flags		= PHY_HAS_INTERRUPT,
 	.probe		= dp83640_probe,
 	.remove		= dp83640_remove,
+	.soft_reset	= dp83640_soft_reset,
 	.config_init	= dp83640_config_init,
 	.ack_interrupt  = dp83640_ack_interrupt,
 	.config_intr    = dp83640_config_intr,
-- 
2.16.3