linux-kernel - [PATCH] PHY: Fix no autoneg corner case

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Message-ID: <m3plmhhx6d.fsf@t19.piap.pl>
Date: Wed, 27 Nov 2024 09:56:42 +0100
From: Krzysztof Hałasa <khalasa@...p.pl>
To: netdev <netdev@...r.kernel.org>
Cc: Oliver Neukum <oneukum@...e.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
 Abeni <pabeni@...hat.com>, linux-usb@...r.kernel.org,
 linux-kernel@...r.kernel.org, Jose Ignacio Tornos Martinez
 <jtornosm@...hat.com>, Ming Lei <ming.lei@...hat.com> 
Subject: [PATCH] PHY: Fix no autoneg corner case

phydev->autoneg appears to indicate if autonegotiation is enabled or
not. Unfortunately it's initially set based on the supported capability
rather than the actual hw setting. While in most cases there is no
difference (i.e., autoneg is supported and on by default), certain
adapters (e.g. fiber optics) use fixed settings, configured in hardware.

Now autoneg flag is set only when it's supported and actually used.

Signed-off-by: Krzysztof Hałasa <khalasa@...p.pl>

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 366cf3b2cbb0..6858f512558b 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -3453,7 +3453,7 @@ static int phy_probe(struct device *dev)
 	struct phy_device *phydev = to_phy_device(dev);
 	struct device_driver *drv = phydev->mdio.dev.driver;
 	struct phy_driver *phydrv = to_phy_driver(drv);
-	int err = 0;
+	int err = 0, bmcr;

 	phydev->drv = phydrv;

@@ -3495,8 +3495,12 @@ static int phy_probe(struct device *dev)
 	if (err)
 		goto out;

+	err = bmcr = phy_read(phydev, MII_BMCR);
+	if (err < 0)
+		goto out;
+
 	if (!linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
-			       phydev->supported))
+			       phydev->supported) || !(bmcr & BMCR_ANENABLE))
 		phydev->autoneg = 0;

 	if (linkmode_test_bit(ETHTOOL_LINK_MODE_1000baseT_Half_BIT,

-- 
Krzysztof "Chris" Hałasa

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