netdev - Re: [net-next PATCH] net: phy: correctly check soft

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Date: Mon, 20 Nov 2023 17:49:28 +0100
From: Christian Marangi <ansuelsmth@...il.com>
To: Larysa Zaremba <larysa.zaremba@...el.com>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [net-next PATCH] net: phy: correctly check soft_reset ret ONLY
 if defined for PHY

On Mon, Nov 20, 2023 at 06:15:43PM +0100, Larysa Zaremba wrote:
> On Mon, Nov 20, 2023 at 02:15:40PM +0100, Christian Marangi wrote:
> > soft_reset call for phy_init_hw had multiple revision across the years
> > and the implementation goes back to 2014. Originally was a simple call
> > to write the generic PHY reset BIT, it was then moved to a dedicated
> > function. It was then added the option for PHY driver to define their
> > own special way to reset the PHY. Till this change, checking for ret was
> > correct as it was always filled by either the generic reset or the
> > custom implementation. This changed tho with commit 6e2d85ec0559 ("net:
> > phy: Stop with excessive soft reset"), as the generic reset call to PHY
> > was dropped but the ret check was never made entirely optional and
> > dependent whether soft_reset was defined for the PHY driver or not.
> > 
> > Luckly nothing was ever added before the soft_reset call so the ret
> > check (in the case where a PHY didn't had soft_reset defined) although
> > wrong, never caused problems as ret was init 0 at the start of
> > phy_init_hw.
> > 
> > To prevent any kind of problem and to make the function cleaner and more
> > robust, correctly move the ret check if the soft_reset section making it
> > optional and needed only with the function defined.
> > 
> > Fixes: 6e2d85ec0559 ("net: phy: Stop with excessive soft reset")
> > Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> > ---
> >  drivers/net/phy/phy_device.c | 9 ++++-----
> >  1 file changed, 4 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> > index 2ce74593d6e4..478126f6b5bc 100644
> > --- a/drivers/net/phy/phy_device.c
> > +++ b/drivers/net/phy/phy_device.c
> > @@ -1235,14 +1235,13 @@ int phy_init_hw(struct phy_device *phydev)
> >  
> >  	if (phydev->drv->soft_reset) {
> >  		ret = phydev->drv->soft_reset(phydev);
> > +		if (ret < 0)
> > +			return ret;
> > +
> >  		/* see comment in genphy_soft_reset for an explanation */
> > -		if (!ret)
> > -			phydev->suspended = 0;
> > +		phydev->suspended = 0;
> 
> Are you sure 'suspended' should not be cleared, if soft_reset fails?
> 
> >  	}

Idea is not change current implementation... And before this, suspended
was cleared only with reset not failing.

> >  
> > -	if (ret < 0)
> > -		return ret;
> > -
> >  	ret = phy_scan_fixups(phydev);
> >  	if (ret < 0)
> >  		return ret;
> > -- 
> > 2.40.1
> > 
> > 

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