netdev - [PATCH net-next] net: phy: add GBit master / slave error detection

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Date:   Wed, 18 Jul 2018 08:14:09 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject:  [PATCH net-next] net: phy: add GBit master / slave error detection

Certain PHY's have issues when operating in GBit slave mode and can
be forced to master mode. Examples are RTL8211C, also the Micrel PHY
driver has a DT setting to force master mode.
If two such chips are link partners the autonegotiation will fail.
Standard defines a self-clearing on read, latched-high bit to
indicate this error. Check this bit to inform the user.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/phy/phy_device.c | 5 +++++
 include/uapi/linux/mii.h     | 1 +
 2 files changed, 6 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index b9f5f40a..249c6f75 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1551,6 +1551,11 @@ int genphy_read_status(struct phy_device *phydev)
 			if (lpagb < 0)
 				return lpagb;
 
+			if (lpagb & LPA_1000MSFAIL) {
+				phydev_err(phydev, "Master/Slave resolution failed, maybe conflicting manual settings?\n");
+				return -ENOLINK;
+			}
+
 			adv = phy_read(phydev, MII_CTRL1000);
 			if (adv < 0)
 				return adv;
diff --git a/include/uapi/linux/mii.h b/include/uapi/linux/mii.h
index b5c2fdcf..a5062165 100644
--- a/include/uapi/linux/mii.h
+++ b/include/uapi/linux/mii.h
@@ -136,6 +136,7 @@
 #define CTL1000_ENABLE_MASTER	0x1000
 
 /* 1000BASE-T Status register */
+#define LPA_1000MSFAIL		0x8000	/* Master/Slave resolution failure */
 #define LPA_1000LOCALRXOK	0x2000	/* Link partner local receiver status */
 #define LPA_1000REMRXOK		0x1000	/* Link partner remote receiver status */
 #define LPA_1000FULL		0x0800	/* Link partner 1000BASE-T full duplex */
-- 
2.18.0