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From: Asmaa Mnebhi <asmaa@nvidia.com>
To: <davem@davemloft.net>, <marek.mojik@nic.cz>, <netdev@vger.kernel.org>
CC: Asmaa Mnebhi <asmaa@nvidia.com>, <davthompson@nvidia.com>,
	<linux-kernel@vger.kernel.org>
Subject: [PATCH v2 1/1] net: phy: micrel: Add workaround for incomplete autonegotiation
Date: Wed, 27 Dec 2023 18:16:57 -0500
Message-ID: <20231227231657.15152-1-asmaa@nvidia.com>
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Very rarely, the KSZ9031 fails to complete autonegotiation although it was
initiated via phy_start(). As a result, the link stays down. Restarting
autonegotiation when in this state solves the issue.

Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
---
v1->v2:
- Use msleep() instead of mdelay()

 drivers/net/phy/micrel.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 08e3915001c3..9952a073413f 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1475,6 +1475,7 @@ static int ksz9031_get_features(struct phy_device *phydev)
 
 static int ksz9031_read_status(struct phy_device *phydev)
 {
+	u8 timeout = 10;
 	int err;
 	int regval;
 
@@ -1494,6 +1495,22 @@ static int ksz9031_read_status(struct phy_device *phydev)
 		return genphy_config_aneg(phydev);
 	}
 
+	/* KSZ9031's autonegotiation takes normally 4-5 seconds to complete.
+	 * Occasionally it fails to complete autonegotiation. The workaround is
+	 * to restart it.
+	 */
+        if (phydev->autoneg == AUTONEG_ENABLE) {
+		while (timeout) {
+			if (phy_aneg_done(phydev))
+				break;
+			msleep(1000);
+			timeout--;
+		};
+
+		if (timeout == 0)
+			phy_restart_aneg(phydev);
+	}
+
 	return 0;
 }
 
-- 
2.30.1