netdev - Re: [RFC/RFT 05/23] net: phy: Immediately call adjust_link if only tx_lpi

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Date:   Tue, 28 Mar 2023 00:13:14 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>
Cc:     netdev <netdev@...r.kernel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Oleksij Rempel <o.rempel@...gutronix.de>
Subject: Re: [RFC/RFT 05/23] net: phy: Immediately call adjust_link if only
 tx_lpi_enabled changes

On Mon, Mar 27, 2023 at 07:02:01PM +0100, Russell King (Oracle) wrote:
> On Mon, Mar 27, 2023 at 07:01:43PM +0200, Andrew Lunn wrote:
> > The MAC driver changes its EEE hardware configuration in its
> > adjust_link callback. This is called when auto-neg completes. If
> > set_eee is called with a change to tx_lpi_enabled which does not
> > trigger an auto-neg, it is necessary to call the adjust_link callback
> > so that the MAC is reconfigured to take this change into account.
> > 
> > When setting phydev->eee_active, take tx_lpi_enabled into account, so
> > the MAC drivers don't need to consider tx_lpi_enabled.
> > 
> > Signed-off-by: Andrew Lunn <andrew@...n.ch>
> 
> Hmm..
> 
> > @@ -1619,11 +1619,20 @@ int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
> >  
> >  	mutex_lock(&phydev->lock);
> >  	ret = genphy_c45_ethtool_set_eee(phydev, data);
> > -	if (!ret)
> > +	if (ret >= 0) {
> > +		if (ret == 0) {
> > +			/* auto-neg not triggered */
> > +			if (phydev->tx_lpi_enabled != data->tx_lpi_enabled) {
> > +				phydev->tx_lpi_enabled = data->tx_lpi_enabled;
> > +				if (phydev->link)
> > +					phy_link_up(phydev);
> > +			}
> > +		}
> >  		phydev->tx_lpi_enabled = data->tx_lpi_enabled;
> 
> So we set eee_active depending on tx_lpi_enabled:
> 
> > +			phydev->eee_active = (err & phydev->tx_lpi_enabled);
> 
> However, if tx_lpi_enabled changes state in this function, we don't
> update phydev->eee_active, but it's phydev->eee_active that gets
> passed back to MAC drivers. Is that intentional?

No, that is a bug. I don't think phy_check_link_status() can be called
here, since we might not be in state RUNNING. So a bit of refactoring
is required to add a function which can update phydev->eee_active.

Thanks
	Andrew