Subject: [PATCH 5/5] net: stmmac: Speed down the PHY if WoL to save energy

From: Jisheng Zhang <[email-masked]>
Date: Mon, 27 Jul 2020 19:05:20 +0800

When WoL is enabled and the machine is powered off, the PHY remains
waiting for wakeup events at max speed, which is a waste of energy.

Slow down the PHY speed before stopping the ethernet if WoL is enabled,

Signed-off-by: Jisheng Zhang <[email-masked]>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 32c0c9647b87..89b2b3472852 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2823,6 +2823,8 @@ static int stmmac_open(struct net_device *dev)
 	stmmac_init_coalesce(priv);
 
 	phylink_start(priv->phylink);
+	/* We may have called phylink_speed_down before */
+	phylink_speed_up(priv->phylink);
 
 	/* Request the IRQ lines */
 	ret = request_irq(dev->irq, stmmac_interrupt,
@@ -2896,6 +2898,8 @@ static int stmmac_release(struct net_device *dev)
 	if (priv->eee_enabled)
 		del_timer_sync(&priv->eee_ctrl_timer);
 
+	if (device_may_wakeup(priv->device))
+		phylink_speed_down(priv->phylink, false);
 	/* Stop and disconnect the PHY */
 	phylink_stop(priv->phylink);
 	phylink_disconnect_phy(priv->phylink);
@@ -5095,6 +5099,8 @@ int stmmac_suspend(struct device *dev)
 	} else {
 		mutex_unlock(&priv->lock);
 		rtnl_lock();
+		if (device_may_wakeup(priv->device))
+			phylink_speed_down(priv->phylink, false);
 		phylink_stop(priv->phylink);
 		rtnl_unlock();
 		mutex_lock(&priv->lock);
@@ -5207,6 +5213,8 @@ int stmmac_resume(struct device *dev)
 	if (!device_may_wakeup(priv->device) || !priv->plat->pmt) {
 		rtnl_lock();
 		phylink_start(priv->phylink);
+		/* We may have called phylink_speed_down before */
+		phylink_speed_up(priv->phylink);
 		rtnl_unlock();
 	}
 
-- 
2.28.0.rc0