netdev - [PATCH] net: phy: phy_device: fix PHY WOL enabled, PM failed to suspend

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Date: Fri, 28 Jun 2024 14:03:18 +0800
From: Youwan Wang <youwan@...china.com>
To: andrew@...n.ch
Cc: hkallweit1@...il.com,
	linux@...linux.org.uk,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Youwan Wang <youwan@...china.com>
Subject: [PATCH] net: phy: phy_device: fix PHY WOL enabled, PM failed to suspend

If the PHY of the mido bus is enabled with Wake-on-LAN (WOL),
we cannot suspend the PHY. Although the WOL status has been
checked in phy_suspend(), returning -EBUSY(-16) would cause
the Power Management (PM) to fail to suspend. Since
phy_suspend() is an exported symbol (EXPORT_SYMBOL),
timely error reporting is needed. Therefore, an additional
check is performed here. If the PHY of the mido bus is enabled
with WOL, we skip calling phy_suspend() to avoid PM failure.

log:
[  322.631362] OOM killer disabled.
[  322.631364] Freezing remaining freezable tasks
[  322.632536] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
[  322.632540] printk: Suspending console(s) (use no_console_suspend to debug)
[  322.633052] YT8521 Gigabit Ethernet stmmac-0:01:
PM: dpm_run_callback(): mdio_bus_phy_suspend+0x0/0x110 [libphy] returns -16
[  322.633071] YT8521 Gigabit Ethernet stmmac-0:01:
PM: failed to suspend: error -16
[  322.669699] PM: Some devices failed to suspend, or early wake event detected
[  322.669949] OOM killer enabled.
[  322.669951] Restarting tasks ... done.
[  322.671008] random: crng reseeded on system resumption
[  322.671014] PM: suspend exit

If the YT8521 driver adds phydrv->flags, ask the YT8521 driver to process
WOL at suspend and resume time, the phydev->suspended_by_mdio_bus=1
flag would cause the resume failure.

log:
[  260.814763] YT8521 Gigabit Ethernet stmmac-0:01:
PM: dpm_run_callback():mdio_bus_phy_resume+0x0/0x160 [libphy] returns -95
[  260.814782] YT8521 Gigabit Ethernet stmmac-0:01:
PM: failed to resume: error -95

Signed-off-by: Youwan Wang <youwan@...china.com>
---
 drivers/net/phy/phy_device.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 2ce74593d6e4..c766130e2c41 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -270,6 +270,7 @@ static DEFINE_MUTEX(phy_fixup_lock);
 
 static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 {
+	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
 	struct device_driver *drv = phydev->mdio.dev.driver;
 	struct phy_driver *phydrv = to_phy_driver(drv);
 	struct net_device *netdev = phydev->attached_dev;
@@ -277,6 +278,14 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 	if (!drv || !phydrv->suspend)
 		return false;
 
+	/* If the PHY of the mido bus is enabled with Wake-on-LAN (WOL),
+	 * we cannot suspend the PHY.
+	 */
+	phy_ethtool_get_wol(phydev, &wol);
+	phydev->wol_enabled = !!(wol.wolopts);
+	if (phydev->wol_enabled && !(phydrv->flags & PHY_ALWAYS_CALL_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
-- 
2.25.1