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

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Date:   Mon, 27 Jul 2020 19:05:20 +0800
From:   Jisheng Zhang <Jisheng.Zhang@...aptics.com>
To:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Russell King <linux@...linux.org.uk>
Cc:     netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 5/5] net: stmmac: Speed down the PHY if WoL to save energy

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 <Jisheng.Zhang@...aptics.com>
---
 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