[PATCH net-next v5 5/6] net: usb: lan78xx: Integrate EEE support with phylink LPI API

Oleksij Rempel
2025-03-19T08:50:01Z

Refactor Energy-Efficient Ethernet (EEE) support in the LAN78xx driver to
fully integrate with the phylink Low Power Idle (LPI) API. This includes:

- Replacing direct calls to `phy_ethtool_get_eee` and `phy_ethtool_set_eee`
with `phylink_ethtool_get_eee` and `phylink_ethtool_set_eee`.
- Implementing `.mac_enable_tx_lpi` and `.mac_disable_tx_lpi` to control
LPI transitions via phylink.
- Configuring `lpi_timer_default` to align with recommended values from
LAN7800 documentation.
- ensure EEE is disabled on controller reset

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
changes v5:
- remove redundant error prints
changes v2:
- use latest PHYlink TX_LPI API
---
drivers/net/usb/lan78xx.c | 111 +++++++++++++++++++++++---------------
1 file changed, 67 insertions(+), 44 deletions(-)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index 9ff8e7850e1e..074ac4d1cbcb 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -1785,54 +1785,15 @@ static int lan78xx_set_wol(struct net_device *netdev,
static int lan78xx_get_eee(struct net_device *net, struct ethtool_keee *edata)
{
struct lan78xx_net *dev = netdev_priv(net);
- struct phy_device *phydev = net->phydev;
- int ret;
- u32 buf;
-
- ret = usb_autopm_get_interface(dev->intf);
- if (ret < 0)
- return ret;
-
- ret = phy_ethtool_get_eee(phydev, edata);
- if (ret < 0)
- goto exit;
-
- ret = lan78xx_read_reg(dev, MAC_CR, &buf);
- if (buf & MAC_CR_EEE_EN_) {
- /* EEE_TX_LPI_REQ_DLY & tx_lpi_timer are same uSec unit */
- ret = lan78xx_read_reg(dev, EEE_TX_LPI_REQ_DLY, &buf);
- edata->tx_lpi_timer = buf;
- } else {
- edata->tx_lpi_timer = 0;
- }
-
- ret = 0;
-exit:
- usb_autopm_put_interface(dev->intf);

- return ret;
+ return phylink_ethtool_get_eee(dev->phylink, edata);
}

static int lan78xx_set_eee(struct net_device *net, struct ethtool_keee *edata)
{
struct lan78xx_net *dev = netdev_priv(net);
- int ret;
- u32 buf;
-
- ret = usb_autopm_get_interface(dev->intf);
- if (ret < 0)
- return ret;

- ret = phy_ethtool_set_eee(net->phydev, edata);
- if (ret < 0)
- goto out;
-
- buf = (u32)edata->tx_lpi_timer;
- ret = lan78xx_write_reg(dev, EEE_TX_LPI_REQ_DLY, buf);
-out:
- usb_autopm_put_interface(dev->intf);
-
- return ret;
+ return phylink_ethtool_set_eee(dev->phylink, edata);
}

static void lan78xx_get_drvinfo(struct net_device *net,
@@ -2470,10 +2431,50 @@ static void lan78xx_mac_link_up(struct phylink_config *config,
ERR_PTR(ret));
}

+static int lan78xx_mac_eee_enable(struct lan78xx_net *dev, bool enable)
+{
+ u32 mac_cr = 0;
+
+ if (enable)
+ mac_cr |= MAC_CR_EEE_EN_;
+
+ /* make sure TXEN and RXEN are disabled before reconfiguring MAC */
+ return lan78xx_update_reg(dev, MAC_CR, MAC_CR_EEE_EN_, mac_cr);
+}
+
+static void lan78xx_mac_disable_tx_lpi(struct phylink_config *config)
+{
+ struct net_device *net = to_net_dev(config->dev);
+ struct lan78xx_net *dev = netdev_priv(net);
+
+ lan78xx_mac_eee_enable(dev, false);
+}
+
+static int lan78xx_mac_enable_tx_lpi(struct phylink_config *config, u32 timer,
+ bool tx_clk_stop)
+{
+ struct net_device *net = to_net_dev(config->dev);
+ struct lan78xx_net *dev = netdev_priv(net);
+ int ret;
+
+ /* Software should only change this field when Energy Efficient
+ * Ethernet Enable (EEEEN) is cleared. We ensure that by clearing
+ * EEEEN during probe, and phylink itself guarantees that
+ * mac_disable_tx_lpi() will have been previously called.
+ */
+ ret = lan78xx_write_reg(dev, EEE_TX_LPI_REQ_DLY, timer);
+ if (ret < 0)
+ return ret;
+
+ return lan78xx_mac_eee_enable(dev, true);
+}
+
static const struct phylink_mac_ops lan78xx_phylink_mac_ops = {
.mac_config = lan78xx_mac_config,
.mac_link_down = lan78xx_mac_link_down,
.mac_link_up = lan78xx_mac_link_up,
+ .mac_disable_tx_lpi = lan78xx_mac_disable_tx_lpi,
+ .mac_enable_tx_lpi = lan78xx_mac_enable_tx_lpi,
};

static struct phy_device *lan7801_phy_init(struct lan78xx_net *dev)
@@ -2528,6 +2529,26 @@ static int lan78xx_phylink_setup(struct lan78xx_net *dev)
pc->mac_capabilities = MAC_SYM_PAUSE | MAC_ASYM_PAUSE | MAC_10 |
MAC_100 | MAC_1000FD;
pc->mac_managed_pm = true;
+ pc->lpi_capabilities = MAC_100FD | MAC_1000FD;
+ /*
+ * Default TX LPI (Low Power Idle) request delay count is set to 50us.
+ *
+ * Source: LAN7800 Documentation, DS00001992H, Section 15.1.57, Page 204.
+ *
+ * Reasoning:
+ * According to the application note in the LAN7800 documentation, a
+ * zero delay may negatively impact the TX data path’s ability to
+ * support Gigabit operation. A value of 50us is recommended as a
+ * reasonable default when the part operates at Gigabit speeds,
+ * balancing stability and power efficiency in EEE mode. This delay can
+ * be increased based on performance testing, as EEE is designed for
+ * scenarios with mostly idle links and occasional bursts of full
+ * bandwidth transmission. The goal is to ensure reliable Gigabit
+ * performance without overly aggressive power optimization during
+ * inactive periods.
+ */
+ pc->lpi_timer_default = 50;
+ pc->eee_enabled_default = true;

if (dev->chipid == ID_REV_CHIP_ID_7801_) {
phy_interface_set_rgmii(pc->supported_interfaces);
@@ -2538,6 +2559,10 @@ static int lan78xx_phylink_setup(struct lan78xx_net *dev)
link_interface = PHY_INTERFACE_MODE_INTERNAL;
}

+ memcpy(dev->phylink_config.lpi_interfaces,
+ dev->phylink_config.supported_interfaces,
+ sizeof(dev->phylink_config.lpi_interfaces));
+
phylink = phylink_create(pc, dev->net->dev.fwnode,
link_interface, &lan78xx_phylink_mac_ops);
if (IS_ERR(phylink))
@@ -2607,8 +2632,6 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
return ret;
}

- phy_support_eee(phydev);
-
if (phydev->mdio.dev.of_node) {
u32 reg;
int len;
@@ -3131,7 +3154,7 @@ static int lan78xx_reset(struct lan78xx_net *dev)
if (ret < 0)
return ret;

- buf &= ~(MAC_CR_AUTO_DUPLEX_ | MAC_CR_AUTO_SPEED_);
+ buf &= ~(MAC_CR_AUTO_DUPLEX_ | MAC_CR_AUTO_SPEED_ | MAC_CR_EEE_EN_);

/* LAN7801 only has RGMII mode */
if (dev->chipid == ID_REV_CHIP_ID_7801_)
--
2.39.5