[PATCH v2 2/2] net: phylink: use PHY-autonomous EEE when MAC LPI is unavailable

Phylink currently treats a MAC which implements the EEE operations but
has no LPI capability for the attached interface as incapable of EEE. It
disables PHY EEE during attach and rejects ethtool EEE requests even when
the PHY can generate Tx LPI autonomously.

Use the phylib LPI-provider API during PHY bring-up. Prefer the MAC when
it supports LPI on the configured interface. For a PHY which can change
its interface with link speed, select the MAC only when every possible
interface supports LPI; otherwise keep one PHY provider across transitions.
Fall back to a configurable autonomous PHY when the MAC is unavailable.

When the PHY is selected, preserve its full EEE advertisement, route Tx
LPI configuration through phylib, and keep the MAC LPI path disabled. Only
restrict EEE modes to the MAC capability mask when the MAC is the selected
provider. Use the recorded provider for ethtool decisions rather than an
interface value which may not yet represent an established link.

If neither provider is usable, retain the existing EEE-disable and
-EOPNOTSUPP behaviour. This does not add a userspace provider selector; the
difference between MAC-managed and PHY-autonomous EEE remains an
implementation detail.

Signed-off-by: James Hilliard <[email protected]>
---
Changes v1 -> v2:
  - use the explicit phylib LPI-provider selection API
  - evaluate MAC LPI support for the attached PHY interface
  - require MAC LPI support on every possible interface for PHYs that can
    change interface with link speed
  - fall back to autonomous PHY LPI only when supported and keep EEE
    unavailable when neither provider is usable
---
 drivers/net/phy/phylink.c | 89 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 78 insertions(+), 11 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 18d2ead97aa5..f644524d627e 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1512,6 +1512,47 @@ static void phylink_deactivate_lpi(struct phylink *pl)
 	}
 }
 
+static bool phylink_phy_supports_autonomous_eee(struct phy_device *phy)
+{
+	return phy && phy_has_autonomous_eee(phy);
+}
+
+static bool phylink_phy_manages_eee(struct phy_device *phy)
+{
+	return phy &&
+	       phy->eee_lpi_provider == PHY_EEE_LPI_PROVIDER_PHY;
+}
+
+static bool phylink_mac_manages_eee(struct phy_device *phy)
+{
+	return phy &&
+	       phy->eee_lpi_provider == PHY_EEE_LPI_PROVIDER_MAC;
+}
+
+static bool
+phylink_mac_supports_eee_interface(struct phylink *pl,
+				   phy_interface_t interface)
+{
+	return pl->mac_supports_eee &&
+	       test_bit(interface, pl->config->lpi_interfaces);
+}
+
+static bool phylink_mac_supports_eee_phy(struct phylink *pl,
+					 struct phy_device *phy,
+					 phy_interface_t interface)
+{
+	if (!pl->mac_supports_eee)
+		return false;
+
+	/* Keep one provider for PHYs which change their interface with speed. */
+	if (!phy_interface_empty(phy->possible_interfaces))
+		return bitmap_subset(phy->possible_interfaces,
+				     pl->config->lpi_interfaces,
+				     PHY_INTERFACE_MODE_MAX);
+
+	return phylink_mac_supports_eee_interface(pl, interface);
+}
+
 static void phylink_activate_lpi(struct phylink *pl)
 {
 	int err;
@@ -2090,6 +2131,8 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy,
 {
 	struct phylink_link_state config;
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(supported);
+	bool phy_eee;
+	bool mac_eee;
 	char *irq_str;
 	int ret;
 
@@ -2106,6 +2149,8 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy,
 	linkmode_copy(supported, phy->supported);
 	linkmode_copy(config.advertising, phy->advertising);
 	config.interface = interface;
+	mac_eee = phylink_mac_supports_eee_phy(pl, phy, interface);
+	phy_eee = !mac_eee && phylink_phy_supports_autonomous_eee(phy);
 
 	ret = phylink_validate_phy(pl, phy, supported, &config);
 	if (ret) {
@@ -2141,10 +2186,21 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy,
 	/* Restrict the phy advertisement according to the MAC support. */
 	linkmode_copy(phy->advertising, config.advertising);
 
+	if (pl->mac_supports_eee) {
+		/* Convert the MAC's LPI capabilities to linkmodes. */
+		linkmode_zero(pl->supported_lpi);
+		phylink_caps_to_linkmodes(pl->supported_lpi,
+					  pl->config->lpi_capabilities);
+	}
+
 	/* If the MAC supports phylink managed EEE, restrict the EEE
 	 * advertisement according to the MAC's LPI capabilities.
 	 */
-	if (pl->mac_supports_eee) {
+	if (mac_eee) {
+		ret = phy_disable_autonomous_eee(phy);
+		if (ret)
+			goto out_unlock;
+
 		/* If EEE is enabled, then we need to call phy_support_eee()
 		 * to ensure that the advertising mask is appropriately set.
 		 * This also enables EEE at the PHY.
@@ -2155,24 +2211,30 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy,
 		phy->eee_cfg.tx_lpi_enabled = pl->eee_cfg.tx_lpi_enabled;
 		phy->eee_cfg.tx_lpi_timer = pl->eee_cfg.tx_lpi_timer;
 
-		/* Convert the MAC's LPI capabilities to linkmodes */
-		linkmode_zero(pl->supported_lpi);
-		phylink_caps_to_linkmodes(pl->supported_lpi,
-					  pl->config->lpi_capabilities);
-
 		/* Restrict the PHYs EEE support/advertisement to the modes
 		 * that the MAC supports.
 		 */
 		linkmode_and(phy->advertising_eee, phy->advertising_eee,
 			     pl->supported_lpi);
+	} else if (phy_eee) {
+		if (pl->eee_cfg.eee_enabled)
+			phy_advertise_eee_all(phy);
+
+		phy->eee_cfg = pl->eee_cfg;
+		ret = phy_support_autonomous_eee(phy);
+		if (ret)
+			goto out_unlock;
 	} else if (pl->mac_supports_eee_ops) {
 		/* MAC supports phylink EEE, but wants EEE always disabled. */
 		phy_disable_eee(phy);
 	}
 
+out_unlock:
 	mutex_unlock(&pl->state_mutex);
 	mutex_unlock(&phy->lock);
 	mutex_unlock(&pl->phydev_mutex);
+	if (ret)
+		return ret;
 
 	phylink_dbg(pl,
 		    "phy: %s setting supported %*pb advertising %*pb\n",
@@ -3300,17 +3362,20 @@ EXPORT_SYMBOL_GPL(phylink_get_eee_err);
  */
 int phylink_ethtool_get_eee(struct phylink *pl, struct ethtool_keee *eee)
 {
+	bool mac_eee;
 	int ret = -EOPNOTSUPP;
 
 	ASSERT_RTNL();
+	mac_eee = phylink_mac_manages_eee(pl->phydev);
 
-	if (pl->mac_supports_eee_ops && !pl->mac_supports_eee)
+	if (pl->mac_supports_eee_ops && !mac_eee &&
+	    !phylink_phy_manages_eee(pl->phydev))
 		return ret;
 
 	if (pl->phydev) {
 		ret = phy_ethtool_get_eee(pl->phydev, eee);
 		/* Restrict supported linkmode mask */
-		if (ret == 0 && pl->mac_supports_eee_ops)
+		if (ret == 0 && mac_eee)
 			linkmode_and(eee->supported, eee->supported,
 				     pl->supported_lpi);
 	}
@@ -3326,10 +3391,11 @@ EXPORT_SYMBOL_GPL(phylink_ethtool_get_eee);
  */
 int phylink_ethtool_set_eee(struct phylink *pl, struct ethtool_keee *eee)
 {
-	bool mac_eee = pl->mac_supports_eee;
+	bool mac_eee;
 	int ret = -EOPNOTSUPP;
 
 	ASSERT_RTNL();
+	mac_eee = phylink_mac_manages_eee(pl->phydev);
 
 	phylink_dbg(pl, "mac %s phylink EEE%s, adv %*pbl, LPI%s timer %uus\n",
 		    mac_eee ? "supports" : "does not support",
@@ -3337,12 +3403,13 @@ int phylink_ethtool_set_eee(struct phylink *pl, struct ethtool_keee *eee)
 		    __ETHTOOL_LINK_MODE_MASK_NBITS, eee->advertised,
 		    eee->tx_lpi_enabled ? " enabled" : "", eee->tx_lpi_timer);
 
-	if (pl->mac_supports_eee_ops && !mac_eee)
+	if (pl->mac_supports_eee_ops && !mac_eee &&
+	    !phylink_phy_manages_eee(pl->phydev))
 		return ret;
 
 	if (pl->phydev) {
 		/* Restrict advertisement mask */
-		if (pl->mac_supports_eee_ops)
+		if (mac_eee)
 			linkmode_and(eee->advertised, eee->advertised,
 				     pl->supported_lpi);
 		ret = phy_ethtool_set_eee(pl->phydev, eee);

-- 
2.53.0