[PATCH net-next v2 2/2] net: phy: improve checks when to suspend the PHY

[Heiner Kallweit <hkallweit1@gmail.com>]

If the parent of the MDIO bus is runtime-suspended, we may not be able
to access the MDIO bus. Therefore add a check for this situation.

So far phy_suspend() only checks for WoL being enabled, other checks
are in mdio_bus_phy_may_suspend(). Improve this and move all checks
to a new function phy_may_suspend() and call it from phy_suspend().

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- Check for MDIO bus parent being runtime-suspended before calling
  phy_ethtool_get_wol() which could access the MDIO bus.
---
 drivers/net/phy/phy_device.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 1662781fb..bc6a002b1 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_bus_parent = phydev->mdio.bus->parent;
+	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
 
-	if (!drv || !phydrv->suspend)
+	if (phydev->suspended || !drv || !phydrv->suspend)
+		return false;
+
+	/* 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_bus_parent && pm_runtime_suspended(mdio_bus_parent))
+		return false;
+
+	/* If the device has WOL enabled, we cannot suspend the PHY */
+	phy_ethtool_get_wol(phydev, &wol);
+	if (wol.wolopts)
 		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);
 }
 
@@ -1162,13 +1174,10 @@ 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);
-- 
2.17.0