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

[Kunihiko Hayashi]

Hi Heiner,

On Mon, 17 Dec 2018 19:43:31 +0100 <hkallweit1@xxxxxxxxx> wrote:

> On 17.12.2018 19:41, Heiner Kallweit wrote:
> > On 17.12.2018 07:41, Kunihiko Hayashi wrote:
> >> 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@xxxxxxxxxxxxx> 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.
> >>>
> > This convenience function and the related change to phy_stop() are part of
> > the following already and don't need to be part of your patch.
> > https://patchwork.ozlabs.org/patch/1014171/

I see. I'll follow your patch when necessary.

> >>> Suggested-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> >>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
> >>> ---
> >>>
> >>> 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;
> > 
> > I'm wondering whether we need to do this. If the PHY is attached,
> > then mdio_bus_phy_suspend() calls phy_stop_machine() which does
> > exactly the same. If the PHY is not attached, then we don't have
> > to do anything. Therefore I think we just have to do the same as
> > in mdio_bus_phy_resume():
> > 
> > if (phydev->attached_dev && phydev->adjust_link)
> > 	phy_start_machine(phydev);

Agreed.

Although the original code changed phydev->state,
it seems that it's only enough to
- call phy_stop_machine() in mdio_bus_phy_suspend()
- call phy_start_machine() in mdio_bus_phy_resume() and mdio_bus_phy_restore()
if the PHY is attached.

> > Can you test this?

I tested your code instead of applying my entire patch, and I confirmed
that the code solved the issue in my environment.

Do you make new patch instead of my patch?
(and I can add Reported-by: for the issue and Tested-by:)

Thank you,


> > 
> Sorry for the confusion, this comment is related to the next part
> of your patch.
> 
> >>>  	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
> >>
> >>
> >>
> > 

---
Best Regards,
Kunihiko Hayashi