linux-kernel - Re: [net-next,v3] net: phy: phy_device: fix PHY WOL enabled, PM failed to suspend

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Message-ID: <46b36141-aae0-468f-be27-cc64b00050d0@intel.com>
Date: Tue, 30 Jul 2024 11:28:32 +0200
From: Wojciech Drewek <wojciech.drewek@...el.com>
To: Youwan Wang <youwan@...china.com>, <linux@...linux.org.uk>
CC: <andrew@...n.ch>, <davem@...emloft.net>, <edumazet@...gle.com>,
	<hkallweit1@...il.com>, <kuba@...nel.org>, <linux-kernel@...r.kernel.org>,
	<netdev@...r.kernel.org>, <pabeni@...hat.com>, Russell King
	<rmk+kernel@...linux.org.uk>
Subject: Re: [net-next,v3] net: phy: phy_device: fix PHY WOL enabled, PM
 failed to suspend



On 30.07.2024 10:15, Youwan Wang wrote:
> 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.
> 
> From the following logs, it has been observed that the phydev->attached_dev
> is NULL, phydev is "stmmac-0:01", it not attached, but it will affect suspend
> and resume.The actually attached "stmmac-0:00" will not dpm_run_callback():
> mdio_bus_phy_suspend().
> 
> init log:
> [    5.932502] YT8521 Gigabit Ethernet stmmac-0:00: attached PHY driver
> (mii_bus:phy_addr=stmmac-0:00, irq=POLL)
> [    5.932512] YT8521 Gigabit Ethernet stmmac-0:01: attached PHY driver
> (mii_bus:phy_addr=stmmac-0:01, irq=POLL)
> [   24.566289] YT8521 Gigabit Ethernet stmmac-0:00: yt8521_read_status,
> link down, media: UTP
> 
> suspend 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
> 
> Add a function that phylib can inquire of the driver whether WoL
> has been enabled at the PHY.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> Signed-off-by: Youwan Wang <youwan@...china.com>
> ---

Reviewed-by: Wojciech Drewek <wojciech.drewek@...el.com>

>  drivers/net/phy/phy_device.c | 19 ++++++++++++++++---
>  1 file changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 7752e9386b40..04a9987ac092 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -279,6 +279,15 @@ static struct phy_driver genphy_driver;
>  static LIST_HEAD(phy_fixup_list);
>  static DEFINE_MUTEX(phy_fixup_lock);
>  
> +static bool phy_drv_wol_enabled(struct phy_device *phydev)
> +{
> +       struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
> +
> +       phy_ethtool_get_wol(phydev, &wol);
> +
> +       return wol.wolopts != 0;
> +}
> +
>  static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
>  {
>  	struct device_driver *drv = phydev->mdio.dev.driver;
> @@ -288,6 +297,12 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
>  	if (!drv || !phydrv->suspend)
>  		return false;
>  
> +	/* If the PHY on the mido bus is not attached but has WOL enabled
> +	 * we cannot suspend the PHY.
> +	 */
> +	if (!netdev && phy_drv_wol_enabled(phydev))
> +		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
> @@ -1975,7 +1990,6 @@ EXPORT_SYMBOL(phy_detach);
>  
>  int phy_suspend(struct phy_device *phydev)
>  {
> -	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
>  	struct net_device *netdev = phydev->attached_dev;
>  	const struct phy_driver *phydrv = phydev->drv;
>  	int ret;
> @@ -1983,8 +1997,7 @@ int phy_suspend(struct phy_device *phydev)
>  	if (phydev->suspended || !phydrv)
>  		return 0;
>  
> -	phy_ethtool_get_wol(phydev, &wol);
> -	phydev->wol_enabled = wol.wolopts ||
> +	phydev->wol_enabled = phy_drv_wol_enabled(phydev) ||
>  			      (netdev && netdev->ethtool->wol_enabled);
>  	/* If the device has WOL enabled, we cannot suspend the PHY */
>  	if (phydev->wol_enabled && !(phydrv->flags & PHY_ALWAYS_CALL_SUSPEND))