linux-kernel - Re: [RFC PATCH net v3] net: phy: Fix the issue that netif always links up after resuming

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Message-Id: <20181217154102.34D9.4A936039@socionext.com>
Date:   Mon, 17 Dec 2018 15:41:03 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH net v3] net: phy: Fix the issue that netif always links up after resuming

Hi,

Gentle ping...
Are there any comments about changes since v2?

v2: https://www.spinics.net/lists/netdev/msg536926.html

Thank you,

On Mon, 3 Dec 2018 17:22:29 +0900 <hayashi.kunihiko@...ionext.com> wrote:

> Even though the link is down before entering hibernation,
> there is an issue that the network interface always links up after resuming
> from hibernation.
> 
> The phydev->state is PHY_READY before enabling the network interface, so
> the link is down. After resuming from hibernation, the phydev->state is
> forcibly set to PHY_UP in mdio_bus_phy_restore(), and the link becomes up.
> 
> This patch adds a new convenient function to check whether the PHY is in
> a started state, and expects to solve the issue by changing phydev->state
> to PHY_UP and calling phy_start_machine() only when the PHY is started.
> 
> Suggested-by: Heiner Kallweit <hkallweit1@...il.com>
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
> ---
> 
> Changes since v2:
>  - add mutex lock/unlock for changing phydev->state
>  - check whether the mutex is locked in phy_is_started()
>  
> Changes since v1:
>  - introduce a new helper function phy_is_started() and use it instead of
>    checking link status
>  - replace checking phydev->state with phy_is_started() in
>    phy_stop_machine()
> 
> drivers/net/phy/phy.c        |  2 +-
>  drivers/net/phy/phy_device.c | 12 +++++++++---
>  include/linux/phy.h          | 13 +++++++++++++
>  3 files changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 1d73ac3..f484d03 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -670,7 +670,7 @@ void phy_stop_machine(struct phy_device *phydev)
>  	cancel_delayed_work_sync(&phydev->state_queue);
>  
>  	mutex_lock(&phydev->lock);
> -	if (phydev->state > PHY_UP && phydev->state != PHY_HALTED)
> +	if (phy_is_started(phydev))
>  		phydev->state = PHY_UP;
>  	mutex_unlock(&phydev->lock);
>  }
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index ab33d17..4897d24 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -309,10 +309,16 @@ static int mdio_bus_phy_restore(struct device *dev)
>  		return ret;
>  
>  	/* The PHY needs to renegotiate. */
> -	phydev->link = 0;
> -	phydev->state = PHY_UP;
> +	mutex_lock(&phydev->lock);
> +	if (phy_is_started(phydev)) {
> +		phydev->state = PHY_UP;
> +		mutex_unlock(&phydev->lock);
> +		phydev->link = 0;
> +		phy_start_machine(phydev);
> +	} else {
> +		mutex_unlock(&phydev->lock);
> +	}
>  
> -	phy_start_machine(phydev);
>  
>  	return 0;
>  }
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index 3ea87f7..dd21537 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -898,6 +898,19 @@ static inline bool phy_is_pseudo_fixed_link(struct phy_device *phydev)
>  }
>  
>  /**
> + * phy_is_started - Convenience function for testing whether a PHY is in
> + * a started state
> + * @phydev: the phy_device struct
> + *
> + * The caller must have taken the phy_device mutex lock.
> + */
> +static inline bool phy_is_started(struct phy_device *phydev)
> +{
> +	WARN_ON(!mutex_is_locked(&phydev->lock));
> +	return phydev->state >= PHY_UP && phydev->state != PHY_HALTED;
> +}
> +
> +/**
>   * phy_write_mmd - Convenience function for writing a register
>   * on an MMD on a given PHY.
>   * @phydev: The phy_device struct
> -- 
> 2.7.4

---
Best Regards,
Kunihiko Hayashi