netdev - [PATCH net] net: phy: fix WoL handling when suspending the PHY

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Message-ID: <4dbcdd2c-96c2-2921-5016-affc8fce1d19@gmail.com>
Date:   Sat, 22 Sep 2018 01:32:55 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Miller <davem@...emloft.net>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net] net: phy: fix WoL handling when suspending the PHY

Actually there's nothing wrong with the two changes, they just
revealed a problem which has been existing before.

Core of the problem is that phy_suspend() suspends the PHY when it
should not because of WoL. phy_suspend() checks for WoL already, but
this works only if the PHY driver handles WoL (what is rarely the case).
Typically WoL is handled by the MAC driver.

phylib knows about this and handles it in mdio_bus_phy_may_suspend(),
but that's used only when suspending the system, not in other cases
like shutdown.

This patch basically moves the check for WoL having been activated
by the MAC driver into phy_suspend(). mdio_bus_phy_resume() now
resumes the PHY only if it's actually suspended. Also don't do
anything in phy_suspend() if the PHY is suspended already.

Last but not least change phy_detach() to call phy_suspend() before
attached_dev is set to NULL. phy_suspend() accesses attached_dev
when checking whether the MAC driver activated WoL.

Fixes: f1e911d5d0df ("r8169: add basic phylib support")
Fixes: e8cfd9d6c772 ("net: phy: call state machine synchronously in phy_stop")
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/phy/phy_device.c | 42 +++++++++++++-----------------------
 1 file changed, 15 insertions(+), 27 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index db1172db1..597747ee7 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -75,23 +75,12 @@ extern struct phy_driver genphy_10g_driver;
 static LIST_HEAD(phy_fixup_list);
 static DEFINE_MUTEX(phy_fixup_lock);
 
-#ifdef CONFIG_PM
-static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
+static bool phy_may_suspend(struct phy_device *phydev)
 {
-	struct device_driver *drv = phydev->mdio.dev.driver;
-	struct phy_driver *phydrv = to_phy_driver(drv);
 	struct net_device *netdev = phydev->attached_dev;
 
-	if (!drv || !phydrv->suspend)
-		return false;
-
-	/* PHY not attached? May suspend if the PHY has not already been
-	 * suspended as part of a prior call to phy_disconnect() ->
-	 * phy_detach() -> phy_suspend() because the parent netdev might be the
-	 * MDIO bus driver and clock gated at this point.
-	 */
 	if (!netdev)
-		return !phydev->suspended;
+		return true;
 
 	/* Don't suspend PHY if the attached netdev parent may wakeup.
 	 * The parent may point to a PCI device, as in tg3 driver.
@@ -103,15 +92,14 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 	 * is the case for devices w/o underlaying pwr. mgmt. aware bus,
 	 * e.g. SoC devices.
 	 */
-	if (device_may_wakeup(&netdev->dev))
-		return false;
-
-	return true;
+	return !device_may_wakeup(&netdev->dev);
 }
 
+#ifdef CONFIG_PM
 static int mdio_bus_phy_suspend(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
+	int ret;
 
 	/* We must stop the state machine manually, otherwise it stops out of
 	 * control, possibly with the phydev->lock held. Upon resume, netdev
@@ -121,25 +109,22 @@ static int mdio_bus_phy_suspend(struct device *dev)
 	if (phydev->attached_dev && phydev->adjust_link)
 		phy_stop_machine(phydev);
 
-	if (!mdio_bus_phy_may_suspend(phydev))
-		return 0;
+	ret = phy_suspend(phydev);
 
-	return phy_suspend(phydev);
+	return ret == -EBUSY ? 0 : ret;
 }
 
 static int mdio_bus_phy_resume(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
-	int ret;
+	int ret = 0;
 
-	if (!mdio_bus_phy_may_suspend(phydev))
-		goto no_resume;
+	if (phydev->suspended)
+		ret = phy_resume(phydev);
 
-	ret = phy_resume(phydev);
 	if (ret < 0)
 		return ret;
 
-no_resume:
 	if (phydev->attached_dev && phydev->adjust_link)
 		phy_start_machine(phydev);
 
@@ -1132,9 +1117,9 @@ void phy_detach(struct phy_device *phydev)
 		sysfs_remove_link(&dev->dev.kobj, "phydev");
 		sysfs_remove_link(&phydev->mdio.dev.kobj, "attached_dev");
 	}
+	phy_suspend(phydev);
 	phydev->attached_dev->phydev = NULL;
 	phydev->attached_dev = NULL;
-	phy_suspend(phydev);
 	phydev->phylink = NULL;
 
 	phy_led_triggers_unregister(phydev);
@@ -1171,9 +1156,12 @@ int phy_suspend(struct phy_device *phydev)
 	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
 	int ret = 0;
 
+	if (phydev->suspended)
+		return 0;
+
 	/* If the device has WOL enabled, we cannot suspend the PHY */
 	phy_ethtool_get_wol(phydev, &wol);
-	if (wol.wolopts)
+	if (wol.wolopts || !phy_may_suspend(phydev))
 		return -EBUSY;
 
 	if (phydev->drv && phydrv->suspend)
-- 
2.19.0