netdev - [PATCH RFC 2/7] net: phy: improve checking for when PHY is allowed to, suspend

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Date:   Wed, 14 Mar 2018 21:16:23 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH RFC 2/7] net: phy: improve checking for when PHY is allowed
 to, suspend

This patch improves and unifies checking for when PHY is allowed to
suspend. New is a check for the parent of the MDIO bus being
runtime-suspended. In this case the MDIO bus may not be accessible and
therefore we don't try to suspend the PHY. Instead we rely on the
parent to suspend all devices on the MDIO bus when it's suspended.

In addition change the behavior to return 0 instead of -EBUSY from
phy_suspend() if we detect a situation where the PHY shouldn't be
suspended. Returning -EBUSY from a suspend callback is supported
for runtime pm, however in case of system suspend it prevents the
system from suspending.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/phy/phy_device.c | 37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 478405e54..a5691536f 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -35,6 +35,7 @@
 #include <linux/io.h>
 #include <linux/uaccess.h>
 #include <linux/of.h>
+#include <linux/pm_runtime.h>
 
 #include <asm/irq.h>
 
@@ -75,14 +76,27 @@ 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;
+	struct device *mdio_parent = phydev->mdio.bus->parent;
+	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
+
+	if (!drv || !phydrv->suspend || phydev->suspended)
+		return false;
+
+	/* If the device has WOL enabled, we cannot suspend the PHY */
+	phy_ethtool_get_wol(phydev, &wol);
+	if (wol.wolopts)
+		return false;
 
-	if (!drv || !phydrv->suspend)
+	/* If the parent of the MDIO bus is runtime-suspended, the MDIO bus may
+	 * not be accessible and we expect the parent to suspend all devices
+	 * on the MDIO bus when it suspends.
+	 */
+	if (mdio_parent && pm_runtime_suspended(mdio_parent))
 		return false;
 
 	/* PHY not attached? May suspend if the PHY has not already been
@@ -91,7 +105,7 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 	 * 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.
@@ -109,6 +123,7 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 	return true;
 }
 
+#ifdef CONFIG_PM
 static int mdio_bus_phy_suspend(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
@@ -121,9 +136,6 @@ 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;
-
 	return phy_suspend(phydev);
 }
 
@@ -132,14 +144,10 @@ static int mdio_bus_phy_resume(struct device *dev)
 	struct phy_device *phydev = to_phy_device(dev);
 	int ret;
 
-	if (!mdio_bus_phy_may_suspend(phydev))
-		goto no_resume;
-
 	ret = phy_resume(phydev);
 	if (ret < 0)
 		return ret;
 
-no_resume:
 	if (phydev->attached_dev && phydev->adjust_link)
 		phy_start_machine(phydev);
 
@@ -1148,13 +1156,10 @@ EXPORT_SYMBOL(phy_detach);
 int phy_suspend(struct phy_device *phydev)
 {
 	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
-	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
 	int ret = 0;
 
-	/* If the device has WOL enabled, we cannot suspend the PHY */
-	phy_ethtool_get_wol(phydev, &wol);
-	if (wol.wolopts)
-		return -EBUSY;
+	if (!phy_may_suspend(phydev))
+		return 0;
 
 	if (phydev->drv && phydrv->suspend)
 		ret = phydrv->suspend(phydev);
-- 
2.16.2