netdev - Re: [PATCH net 2/2] net: phy: fix WoL handling when suspending the PHY

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Message-ID: <6b5a93d4-46c8-7928-eea5-76740071b5a7@gmail.com>
Date:   Mon, 24 Sep 2018 11:21:27 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        David Miller <davem@...emloft.net>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net 2/2] net: phy: fix WoL handling when suspending the
 PHY

On 09/24/2018 11:11 AM, Heiner Kallweit wrote:
> 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.
> 
> This patch uses new member wol_enabled of struct net_device as
> additional criteria in the check when not to suspend the PHY because
> of WoL.
> 
> 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.

Looks fine to me, just a few nits/questions down below:

Reviewed-by: Florian Fainelli <f.fainelli@...il.com>

> 
> 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 | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index af64a9320..6c0195e53 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -93,7 +93,12 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
>  	if (!netdev)
>  		return !phydev->suspended;
>  
> -	/* Don't suspend PHY if the attached netdev parent may wakeup.
> +	if (netdev->wol_enabled)
> +		return false;
> +
> +	/* As lang as not all affected network drivers support the
> +	 * wol_enabled flag, let's check for hints that WoL is enabled.

Typo: as long (sorry for being that nitpicky).

> +	 * Don't suspend PHY if the attached netdev parent may wakeup.
>  	 * The parent may point to a PCI device, as in tg3 driver.
>  	 */
>  	if (netdev->dev.parent && device_may_wakeup(netdev->dev.parent))
> @@ -1132,9 +1137,9 @@ 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);
> @@ -1168,12 +1173,13 @@ EXPORT_SYMBOL(phy_detach);
>  int phy_suspend(struct phy_device *phydev)
>  {
>  	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
> +	struct net_device *netdev = phydev->attached_dev;
>  	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)
> +	if (wol.wolopts || (netdev && netdev->wol_enabled))

Since you moved the phydev->attached_dev assignment to be after
phy_suspend(), do you really need to check for netdev here? Is there
another code path you found that might be running phy_suspend() with a
disconnected PHY? Not a problem per-se, just wondering.
-- 
Florian