netdev - [PATCH net-next 1/3] net: phy: add and use phy_check

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Message-ID: <d2822357-4c1e-a072-632e-a902b04eba7c@gmail.com>
Date:   Wed, 18 Mar 2020 22:29:01 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net-next 1/3] net: phy: add and use phy_check_downshift

So far PHY drivers have to check whether a downshift occurred to be
able to notify the user. To make life of drivers authors a little bit
easier move the downshift notification to phylib. phy_check_downshift()
compares the highest mutually advertised speed with the actual value
of phydev->speed (typically read by the PHY driver from a
vendor-specific register) to detect a downshift.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/phy/phy-core.c | 33 +++++++++++++++++++++++++++++++++
 drivers/net/phy/phy.c      |  1 +
 include/linux/phy.h        |  1 +
 3 files changed, 35 insertions(+)

diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
index e083e7a76..8e861be73 100644
--- a/drivers/net/phy/phy-core.c
+++ b/drivers/net/phy/phy-core.c
@@ -329,6 +329,39 @@ void phy_resolve_aneg_linkmode(struct phy_device *phydev)
 }
 EXPORT_SYMBOL_GPL(phy_resolve_aneg_linkmode);
 
+/**
+ * phy_check_downshift - check whether downshift occurred
+ * @phydev: The phy_device struct
+ *
+ * Check whether a downshift to a lower speed occurred. If this should be the
+ * case warn the user.
+ */
+bool phy_check_downshift(struct phy_device *phydev)
+{
+	__ETHTOOL_DECLARE_LINK_MODE_MASK(common);
+	int i, speed = SPEED_UNKNOWN;
+
+	if (phydev->autoneg == AUTONEG_DISABLE)
+		return false;
+
+	linkmode_and(common, phydev->lp_advertising, phydev->advertising);
+
+	for (i = 0; i < ARRAY_SIZE(settings); i++)
+		if (test_bit(settings[i].bit, common)) {
+			speed = settings[i].speed;
+			break;
+		}
+
+	if (phydev->speed == speed)
+		return false;
+
+	phydev_warn(phydev, "Downshift occurred from negotiated speed %s to actual speed %s, check cabling!\n",
+		    phy_speed_to_str(speed), phy_speed_to_str(phydev->speed));
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(phy_check_downshift);
+
 static int phy_resolve_min_speed(struct phy_device *phydev, bool fdx_only)
 {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(common);
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index d71212a41..067ff5fec 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -507,6 +507,7 @@ static int phy_check_link_status(struct phy_device *phydev)
 		return err;
 
 	if (phydev->link && phydev->state != PHY_RUNNING) {
+		phy_check_downshift(phydev);
 		phydev->state = PHY_RUNNING;
 		phy_link_up(phydev);
 	} else if (!phydev->link && phydev->state != PHY_NOLINK) {
diff --git a/include/linux/phy.h b/include/linux/phy.h
index cb5a2182b..4962766b2 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -698,6 +698,7 @@ static inline bool phy_is_started(struct phy_device *phydev)
 
 void phy_resolve_aneg_pause(struct phy_device *phydev);
 void phy_resolve_aneg_linkmode(struct phy_device *phydev);
+bool phy_check_downshift(struct phy_device *phydev);
 
 /**
  * phy_read - Convenience function for reading a given PHY register
-- 
2.25.1