linux-kernel - Re: [PATCH net-next v1 1/1] net: phy: ax88772a: fix lost pause advertisement configuration

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Date:   Sun, 26 Jun 2022 14:15:49 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Lukas Wunner <lukas@...ner.de>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        kernel@...gutronix.de, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net-next v1 1/1] net: phy: ax88772a: fix lost pause
 advertisement configuration

On Sun, Jun 26, 2022 at 10:58:24AM +0200, Andrew Lunn wrote:
> On Sat, Jun 25, 2022 at 09:17:31AM +0200, Lukas Wunner wrote:
> > On Fri, Jun 24, 2022 at 09:55:58AM +0200, Oleksij Rempel wrote:
> > > In case of asix_ax88772a_link_change_notify() workaround, we run soft
> > > reset which will automatically clear MII_ADVERTISE configuration. The
> > > PHYlib framework do not know about changed configuration state of the
> > > PHY, so we need to save and restore all needed configuration registers.
> > [...]
> > >  static void asix_ax88772a_link_change_notify(struct phy_device *phydev)
> > >  {
> > >  	/* Reset PHY, otherwise MII_LPA will provide outdated information.
> > >  	 * This issue is reproducible only with some link partner PHYs
> > >  	 */
> > > -	if (phydev->state == PHY_NOLINK && phydev->drv->soft_reset)
> > > +	if (phydev->state == PHY_NOLINK && phydev->drv->soft_reset) {
> > > +		struct asix_context context;
> > > +
> > > +		asix_context_save(phydev, &context);
> > > +
> > >  		phydev->drv->soft_reset(phydev);
> > > +
> > > +		asix_context_restore(phydev, &context);
> > > +	}
> > >  }
> > 
> > Hm, how about just calling phy_init_hw()?  That will perform a
> > ->soft_reset() and also restore the configuration, including
> > interrupts (which the above does not, but I guess that's
> > irrelevant as long as the driver uses polling).
> > 
> > Does phy_init_hw() do too much or too little compared to the above
> > and is hence not a viable solution?
> 
> 
> at803x.c has:
> 
>         /* After changing the smart speed settings, we need to perform a
>          * software reset, use phy_init_hw() to make sure we set the
>          * reapply any values which might got lost during software reset.
>          */
>         if (ret == 1)
>                 ret = phy_init_hw(phydev);
> 

Hm, this is not enough to restore/reconfigure advertisement register.
Should I change PHY state to UP and trigger the state machine?

Regards,
Oleksij
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