1 files changed, 39 insertions, 32 deletions

diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
index a4d2d59fceca..66b8c61ca74c 100644
--- a/drivers/net/phy/phy-core.c
+++ b/drivers/net/phy/phy-core.c
@@ -8,7 +8,7 @@
 
 const char *phy_speed_to_str(int speed)
 {
-	BUILD_BUG_ON_MSG(__ETHTOOL_LINK_MODE_MASK_NBITS != 74,
+	BUILD_BUG_ON_MSG(__ETHTOOL_LINK_MODE_MASK_NBITS != 75,
 		"Enum ethtool_link_mode_bit_indices and phylib are out of sync. "
 		"If a speed or mode has been added please update phy_speed_to_str "
 		"and the PHY settings array.\n");
@@ -329,6 +329,44 @@ 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.
+ * Prerequisite for detecting downshift is that PHY driver implements the
+ * read_status callback and sets phydev->speed to the actual link speed.
+ */
+void phy_check_downshift(struct phy_device *phydev)
+{
+	__ETHTOOL_DECLARE_LINK_MODE_MASK(common);
+	int i, speed = SPEED_UNKNOWN;
+
+	phydev->downshifted_rate = 0;
+
+	if (phydev->autoneg == AUTONEG_DISABLE ||
+	    phydev->speed == SPEED_UNKNOWN)
+		return;
+
+	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 (speed == SPEED_UNKNOWN || phydev->speed >= speed)
+		return;
+
+	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));
+
+	phydev->downshifted_rate = 1;
+}
+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);
@@ -489,37 +527,6 @@ int phy_write_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val)
 EXPORT_SYMBOL(phy_write_mmd);
 
 /**
- * __phy_modify_changed() - Convenience function for modifying a PHY register
- * @phydev: a pointer to a &struct phy_device
- * @regnum: register number
- * @mask: bit mask of bits to clear
- * @set: bit mask of bits to set
- *
- * Unlocked helper function which allows a PHY register to be modified as
- * new register value = (old register value & ~mask) | set
- *
- * Returns negative errno, 0 if there was no change, and 1 in case of change
- */
-int __phy_modify_changed(struct phy_device *phydev, u32 regnum, u16 mask,
-			 u16 set)
-{
-	int new, ret;
-
-	ret = __phy_read(phydev, regnum);
-	if (ret < 0)
-		return ret;
-
-	new = (ret & ~mask) | set;
-	if (new == ret)
-		return 0;
-
-	ret = __phy_write(phydev, regnum, new);
-
-	return ret < 0 ? ret : 1;
-}
-EXPORT_SYMBOL_GPL(__phy_modify_changed);
-
-/**
  * phy_modify_changed - Function for modifying a PHY register
  * @phydev: the phy_device struct
  * @regnum: register number to modify