net: phy: Immediately call adjust_link if only tx_lpi_enabled changes

The MAC driver changes its EEE hardware configuration in its
adjust_link callback. This is called when auto-neg
completes. Disabling EEE via eee_enabled false will trigger an
autoneg, and as a result the adjust_link callback will be called with
phydev->enable_tx_lpi set to false. Similarly, eee_enabled set to true
and with a change of advertised link modes will result in a new
autoneg, and a call the adjust_link call.

If set_eee is called with only a change to tx_lpi_enabled which does
not trigger an auto-neg, it is necessary to call the adjust_link
callback so that the MAC is reconfigured to take this change into
account.

When setting phydev->enable_tx_lpi, take both eee_enabled and
tx_lpi_enabled into account, so the MAC drivers just needs to act on
phydev->enable_tx_lpi and not the whole EEE configuration.
The same check should be done for tx_lpi_timer too.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20240302195306.3207716-5-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/phy-c45.c

@@ -1550,6 +1550,8 @@ EXPORT_SYMBOL(genphy_c45_ethtool_get_eee);
  * advertised, but the previously advertised link modes are
  * retained. This allows EEE to be enabled/disabled in a
  * non-destructive way.
+ * Returns either error code, 0 if there was no change, or positive
+ * value if there was a change which triggered auto-neg.
  */
 int genphy_c45_ethtool_set_eee(struct phy_device *phydev,
 			       struct ethtool_keee *data)
@@ -1576,8 +1578,16 @@ int genphy_c45_ethtool_set_eee(struct phy_device *phydev,
 	phydev->eee_enabled = data->eee_enabled;
 
 	ret = genphy_c45_an_config_eee_aneg(phydev);
-	if (ret > 0)
+	if (ret > 0) {
-		return phy_restart_aneg(phydev);
+		ret = phy_restart_aneg(phydev);
+		if (ret < 0)
+			return ret;
+
+		/* explicitly return 1, otherwise (ret > 0) value will be
+		 * overwritten by phy_restart_aneg().
+		 */
+		return 1;
+	}
 
 	return ret;
 }

drivers/net/phy/phy.c

@@ -988,7 +988,8 @@ static int phy_check_link_status(struct phy_device *phydev)
 		if (err < 0)
 			phydev->enable_tx_lpi = false;
 		else
-			phydev->enable_tx_lpi = !!err;
+			phydev->enable_tx_lpi = (err & phydev->eee_cfg.tx_lpi_enabled);
+
 		phy_link_up(phydev);
 	} else if (!phydev->link && phydev->state != PHY_NOLINK) {
 		phydev->state = PHY_NOLINK;
@@ -1659,6 +1660,36 @@ int phy_ethtool_get_eee(struct phy_device *phydev, struct ethtool_keee *data)
 }
 EXPORT_SYMBOL(phy_ethtool_get_eee);
 
+/**
+ * phy_ethtool_set_eee_noneg - Adjusts MAC LPI configuration without PHY
+ *			       renegotiation
+ * @phydev: pointer to the target PHY device structure
+ * @data: pointer to the ethtool_keee structure containing the new EEE settings
+ *
+ * This function updates the Energy Efficient Ethernet (EEE) configuration
+ * for cases where only the MAC's Low Power Idle (LPI) configuration changes,
+ * without triggering PHY renegotiation. It ensures that the MAC is properly
+ * informed of the new LPI settings by cycling the link down and up, which
+ * is necessary for the MAC to adopt the new configuration. This adjustment
+ * is done only if there is a change in the tx_lpi_enabled or tx_lpi_timer
+ * configuration.
+ */
+static void phy_ethtool_set_eee_noneg(struct phy_device *phydev,
+				      struct ethtool_keee *data)
+{
+	if (phydev->eee_cfg.tx_lpi_enabled != data->tx_lpi_enabled ||
+	    phydev->eee_cfg.tx_lpi_timer != data->tx_lpi_timer) {
+		eee_to_eeecfg(&phydev->eee_cfg, data);
+		phydev->enable_tx_lpi = eeecfg_mac_can_tx_lpi(&phydev->eee_cfg);
+		if (phydev->link) {
+			phydev->link = false;
+			phy_link_down(phydev);
+			phydev->link = true;
+			phy_link_up(phydev);
+		}
+	}
+}
+
 /**
  * phy_ethtool_set_eee - set EEE supported and status
  * @phydev: target phy_device struct
@@ -1675,11 +1706,14 @@ int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_keee *data)
 
 	mutex_lock(&phydev->lock);
 	ret = genphy_c45_ethtool_set_eee(phydev, data);
-	if (!ret)
+	if (ret >= 0) {
+		if (ret == 0)
+			phy_ethtool_set_eee_noneg(phydev, data);
 		eee_to_eeecfg(&phydev->eee_cfg, data);
+	}
 	mutex_unlock(&phydev->lock);
 
-	return ret;
+	return ret < 0 ? ret : 0;
 }
 EXPORT_SYMBOL(phy_ethtool_set_eee);