[PATCH net-next] net: phy: call phy_init_hw() in phy resume path

[PATCH net-next] net: phy: call phy_init_hw() in phy resume path

[Biju]

From: Ovidiu Panait <ovidiu.panait.rb@renesas.com>

When mac_managed_pm flag is set, mdio_bus_phy_resume() is skipped, so
phy_init_hw(), which performs soft_reset and config_init, is not called
during resume.

This is inconsistent with the non-mac_managed_pm path, where
mdio_bus_phy_resume() calls phy_init_hw() before phy_resume() on every
resume.

To align both paths, add a phy_init_hw() call at the top of
__phy_resume(), before invoking the driver's resume callback. This
guarantees the PHY undergoes soft reset and re-initialization regardless
of whether PM is managed by the MAC or the MDIO bus.

Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
 drivers/net/phy/phy_device.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 0edff47478c2..8255f4208d66 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2008,6 +2008,10 @@ int __phy_resume(struct phy_device *phydev)
 	if (!phydrv || !phydrv->resume)
 		return 0;
 
+	ret = phy_init_hw(phydev);
+	if (ret)
+		return ret;
+
 	ret = phydrv->resume(phydev);
 	if (!ret)
 		phydev->suspended = false;
-- 
2.43.0

Re: [PATCH net-next] net: phy: call phy_init_hw() in phy resume path

[Russell King (Oracle)]

On Fri, Apr 10, 2026 at 03:29:01PM +0100, Biju wrote:
> From: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
> 
> When mac_managed_pm flag is set, mdio_bus_phy_resume() is skipped, so
> phy_init_hw(), which performs soft_reset and config_init, is not called
> during resume.
> 
> This is inconsistent with the non-mac_managed_pm path, where
> mdio_bus_phy_resume() calls phy_init_hw() before phy_resume() on every
> resume.
> 
> To align both paths, add a phy_init_hw() call at the top of
> __phy_resume(), before invoking the driver's resume callback. This
> guarantees the PHY undergoes soft reset and re-initialization regardless
> of whether PM is managed by the MAC or the MDIO bus.
> 
> Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> ---
>  drivers/net/phy/phy_device.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 0edff47478c2..8255f4208d66 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -2008,6 +2008,10 @@ int __phy_resume(struct phy_device *phydev)
>  	if (!phydrv || !phydrv->resume)
>  		return 0;
>  
> +	ret = phy_init_hw(phydev);
> +	if (ret)
> +		return ret;

Do we want to do this even when phydrv->resume is NULL?

Apart from that, looks fine to me - it seems some paths call
phy_init_hw() can be called with or without phydev->lock held, and
this one will call it with the lock held which seems to be okay.

-- 
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Re: [PATCH net-next] net: phy: call phy_init_hw() in phy resume path

[Russell King (Oracle)]

On Fri, Apr 10, 2026 at 03:51:18PM +0100, Russell King (Oracle) wrote:
> On Fri, Apr 10, 2026 at 03:29:01PM +0100, Biju wrote:
> > From: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
> > 
> > When mac_managed_pm flag is set, mdio_bus_phy_resume() is skipped, so
> > phy_init_hw(), which performs soft_reset and config_init, is not called
> > during resume.
> > 
> > This is inconsistent with the non-mac_managed_pm path, where
> > mdio_bus_phy_resume() calls phy_init_hw() before phy_resume() on every
> > resume.
> > 
> > To align both paths, add a phy_init_hw() call at the top of
> > __phy_resume(), before invoking the driver's resume callback. This
> > guarantees the PHY undergoes soft reset and re-initialization regardless
> > of whether PM is managed by the MAC or the MDIO bus.
> > 
> > Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
> > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> > ---
> >  drivers/net/phy/phy_device.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> > index 0edff47478c2..8255f4208d66 100644
> > --- a/drivers/net/phy/phy_device.c
> > +++ b/drivers/net/phy/phy_device.c
> > @@ -2008,6 +2008,10 @@ int __phy_resume(struct phy_device *phydev)
> >  	if (!phydrv || !phydrv->resume)
> >  		return 0;
> >  
> > +	ret = phy_init_hw(phydev);
> > +	if (ret)
> > +		return ret;
> 
> Do we want to do this even when phydrv->resume is NULL?

I should've also added (sorry, busy packing) - with it always being
called even when phydrv->resume is NULL, it means that the call sites
to phy_resume() in phylib which are preceeded by a call to
phy_init_hw() should have that call removed, otherwise we're going to
be calling phy_init_hw() twice.

As the patch currently stands, that's the case when phydrv->resume
is populated, and I think we should avoid that.

> Apart from that, looks fine to me - it seems some paths call
> phy_init_hw() can be called with or without phydev->lock held, and
> this one will call it with the lock held which seems to be okay.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH net-next] net: phy: call phy_init_hw() in phy resume path

[Andrew Lunn]

> Apart from that, looks fine to me - it seems some paths call
> phy_init_hw() can be called with or without phydev->lock held, and
> this one will call it with the lock held which seems to be okay.

Haven't we had deadlocks in this area before?

Please test with CONFIG_PROVE_LOCKING enabled.

       Andrew

Re: [PATCH net-next] net: phy: call phy_init_hw() in phy resume path

[Russell King (Oracle)]

On Fri, Apr 10, 2026 at 05:15:21PM +0200, Andrew Lunn wrote:
> > Apart from that, looks fine to me - it seems some paths call
> > phy_init_hw() can be called with or without phydev->lock held, and
> > this one will call it with the lock held which seems to be okay.
> 
> Haven't we had deadlocks in this area before?

If we have a problem calling phy_init_hw() with phydev->lock held, then:

phy_state_machine():
        mutex_lock(&phydev->lock);
        state_work = _phy_state_machine(phydev);

_phy_state_machine():
	switch (phydev->state) {
...
        case PHY_CABLETEST:
                err = phydev->drv->cable_test_get_status(phydev, &finished);
                if (err) {
                        phy_abort_cable_test(phydev);

phy_abort_cable_test():
        err = phy_init_hw(phydev);

that path has a problem and needs fixing.


-- 
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FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

RE: [PATCH net-next] net: phy: call phy_init_hw() in phy resume path

[Biju Das]

Hi Russell King,

> -----Original Message-----
> From: Russell King <linux@armlinux.org.uk>
> Sent: 10 April 2026 16:22
> Subject: Re: [PATCH net-next] net: phy: call phy_init_hw() in phy resume path
> 
> On Fri, Apr 10, 2026 at 05:15:21PM +0200, Andrew Lunn wrote:
> > > Apart from that, looks fine to me - it seems some paths call
> > > phy_init_hw() can be called with or without phydev->lock held, and
> > > this one will call it with the lock held which seems to be okay.
> >
> > Haven't we had deadlocks in this area before?
> 
> If we have a problem calling phy_init_hw() with phydev->lock held, then:
> 
> phy_state_machine():
>         mutex_lock(&phydev->lock);
>         state_work = _phy_state_machine(phydev);
> 
> _phy_state_machine():
> 	switch (phydev->state) {
> ...
>         case PHY_CABLETEST:
>                 err = phydev->drv->cable_test_get_status(phydev, &finished);
>                 if (err) {
>                         phy_abort_cable_test(phydev);
> 
> phy_abort_cable_test():
>         err = phy_init_hw(phydev);
> 
> that path has a problem and needs fixing.

These 3 Phy drivers are using the same lock, and it can lead to dead lock.

drivers/net/phy/microchip_t1.c
drivers/net/phy/marvell-88x2222.c
drivers/net/phy/mscc/mscc_main.c

Maybe as you said earlier, moving to phy_resume() will be safer solution.

Cheers,
Biju

Re: [PATCH net-next] net: phy: call phy_init_hw() in phy resume path

[Andrew Lunn]

On Fri, Apr 10, 2026 at 04:22:23PM +0100, Russell King (Oracle) wrote:
> On Fri, Apr 10, 2026 at 05:15:21PM +0200, Andrew Lunn wrote:
> > > Apart from that, looks fine to me - it seems some paths call
> > > phy_init_hw() can be called with or without phydev->lock held, and
> > > this one will call it with the lock held which seems to be okay.
> > 
> > Haven't we had deadlocks in this area before?
> 
> If we have a problem calling phy_init_hw() with phydev->lock held, then:

I thought it was an AB-BA with RTNL?

Lets see what PROVE_LOCKING actually says. I could be remembering
wrongly.

	Andrew