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

[Biju Das]

Hi Russell King/ Andrew,

> -----Original Message-----
> From: Russell King <linux@xxxxxxxxxxxxxxx>
> Sent: 10 April 2026 15:55
> Subject: Re: [PATCH net-next] net: phy: call phy_init_hw() in phy resume path
> 
> 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.


The new patch will be like this, after moving phy_init_hw() without
phydev->lock held. Please let me know are you ok with this?


diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 0edff47478c2..4a2b19d39373 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -396,10 +396,6 @@ static __maybe_unused int mdio_bus_phy_resume(struct device *dev)
 	WARN_ON(phydev->state != PHY_HALTED && phydev->state != PHY_READY &&
 		phydev->state != PHY_UP);
 
-	ret = phy_init_hw(phydev);
-	if (ret < 0)
-		return ret;
-
 	ret = phy_resume(phydev);
 	if (ret < 0)
 		return ret;
@@ -1857,16 +1853,14 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 	if (dev)
 		netif_carrier_off(phydev->attached_dev);
 
-	/* Do initial configuration here, now that
+	/* Do initial configuration inside phy_init_hw(), now that
 	 * we have certain key parameters
 	 * (dev_flags and interface)
 	 */
-	err = phy_init_hw(phydev);
+	err = phy_resume(phydev);
 	if (err)
 		goto error;
 
-	phy_resume(phydev);
-
 	/**
 	 * If the external phy used by current mac interface is managed by
 	 * another mac interface, so we should create a device link between
@@ -2020,6 +2014,10 @@ int phy_resume(struct phy_device *phydev)
 {
 	int ret;
 
+	ret = phy_init_hw(phydev);
+	if (ret)
+		return ret;
+
 	mutex_lock(&phydev->lock);
 	ret = __phy_resume(phydev);
 	mutex_unlock(&phydev->lock);
--