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@xxxxxxxxxxx>
> > 
> > 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@xxxxxxxxxxx>
> > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > ---
> >  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.

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