Re: [PATCH net] net: phy: Avoid WARN_ON for PHY_NOLINK during resuming

[Kunihiko Hayashi]

Hi Heiner,

Thank you for your comment.

On 2022/10/21 17:38, Heiner Kallweit wrote:
> On 21.10.2022 09:41, Kunihiko Hayashi wrote:
> > When resuming from sleep, if there is a time lag from link-down to link-up
> > due to auto-negotiation, the phy status has been still PHY_NOLINK, so
> > WARN_ON dump occurs in mdio_bus_phy_resume(). For example, UniPhier AVE
> > ethernet takes about a few seconds to link up after resuming.
> That autoneg takes some time is normal. If this would actually the root
> cause then basically every driver should be affected. But it's not.

Although the auto-neg should happen normally, I'm not sure about other
platforms.

> > To avoid this issue, should remove PHY_NOLINK the WARN_ON conditions.
> >
> > Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
> > ---
> >   drivers/net/phy/phy_device.c | 8 ++++----
> >   1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> > index 57849ac0384e..c647d027bb5d 100644
> > --- a/drivers/net/phy/phy_device.c
> > +++ b/drivers/net/phy/phy_device.c
> > @@ -318,12 +318,12 @@ static __maybe_unused int mdio_bus_phy_resume(struct
> > device *dev)
> >   	phydev->suspended_by_mdio_bus = 0;
> >
> >   	/* If we managed to get here with the PHY state machine in a state
> > -	 * neither PHY_HALTED, PHY_READY nor PHY_UP, this is an indication
> > -	 * that something went wrong and we should most likely be using
> > -	 * MAC managed PM, but we are not.
> > +	 * neither PHY_HALTED, PHY_READY, PHY_UP nor PHY_NOLINK, this is an
> > +	 * indication that something went wrong and we should most likely
> > +	 * be using MAC managed PM, but we are not.
> >   	 */
>
> Did you read the comment you're changing? ave_resume() calls phy_resume(),
> so you should follow the advice in the comment.

I understand something is wrong with "PHY_NOLINK" here, and need to investigate
the root cause of the phy state issue.

Thank you,

---
Best Regards
Kunihiko Hayashi