Subject: Re: [PATCH net-next v13 12/15] net: stmmac: Fixed failure to set network speed to 1000.

From: "Russell King (Oracle)" <[email-masked]>
Date: Fri, 5 Jul 2024 12:31:45 +0100

On Fri, Jul 05, 2024 at 07:17:01PM +0800, Yanteng Si wrote:
> 在 2024/7/4 04:33, Russell King (Oracle) 写道:
> > I think we should "lie" to userspace rather than report how the
> > hardware was actually programmed - again, because that's what would
> > happen with Marvell Alaska.
> > 
> > > What about other speeds? Is this limited to 1G? Since we have devices
> > > without auto-neg for 2500BaseX i assume it is not an issue there.
> > 1000base-X can have AN disabled - that's not an issue. Yes, there's
> > the ongoing issues with 2500base-X. 10Gbase-T wording is similar to
> > 1000base-T, so we probably need to do similar there. Likely also the
> > case for 2500base-T and 5000base-T as well.
> > 
> > So I'm thinking of something like this (untested):
> > 
> > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> > index 6c6ec9475709..197c4d5ab55b 100644
> > --- a/drivers/net/phy/phy_device.c
> > +++ b/drivers/net/phy/phy_device.c
> > @@ -2094,22 +2094,20 @@ EXPORT_SYMBOL(phy_reset_after_clk_enable);
> >   /**
> >    * genphy_config_advert - sanitize and advertise auto-negotiation parameters
> >    * @phydev: target phy_device struct
> > + * @advert: auto-negotiation parameters to advertise
> >    *
> >    * Description: Writes MII_ADVERTISE with the appropriate values,
> >    *   after sanitizing the values to make sure we only advertise
> >    *   what is supported.  Returns < 0 on error, 0 if the PHY's advertisement
> >    *   hasn't changed, and > 0 if it has changed.
> >    */
> > -static int genphy_config_advert(struct phy_device *phydev)
> > +static int genphy_config_advert(struct phy_device *phydev,
> > +				const unsigned long *advert)
> >   {
> >   	int err, bmsr, changed = 0;
> >   	u32 adv;
> > -	/* Only allow advertising what this PHY supports */
> > -	linkmode_and(phydev->advertising, phydev->advertising,
> > -		     phydev->supported);
> > -
> > -	adv = linkmode_adv_to_mii_adv_t(phydev->advertising);
> > +	adv = linkmode_adv_to_mii_adv_t(advert);
> >   	/* Setup standard advertisement */
> >   	err = phy_modify_changed(phydev, MII_ADVERTISE,
> > @@ -2132,7 +2130,7 @@ static int genphy_config_advert(struct phy_device *phydev)
> >   	if (!(bmsr & BMSR_ESTATEN))
> >   		return changed;
> > -	adv = linkmode_adv_to_mii_ctrl1000_t(phydev->advertising);
> > +	adv = linkmode_adv_to_mii_ctrl1000_t(advert);
> >   	err = phy_modify_changed(phydev, MII_CTRL1000,
> >   				 ADVERTISE_1000FULL | ADVERTISE_1000HALF,
> > @@ -2356,6 +2354,9 @@ EXPORT_SYMBOL(genphy_check_and_restart_aneg);
> >    */
> >   int __genphy_config_aneg(struct phy_device *phydev, bool changed)
> >   {
> > +	__ETHTOOL_DECLARE_LINK_MODE_MASK(fixed_advert);
> > +	const struct phy_setting *set;
> > +	unsigned long *advert;
> >   	int err;
> >   	err = genphy_c45_an_config_eee_aneg(phydev);
> > @@ -2370,10 +2371,25 @@ int __genphy_config_aneg(struct phy_device *phydev, bool changed)
> >   	else if (err)
> >   		changed = true;
> > -	if (AUTONEG_ENABLE != phydev->autoneg)
> > +	if (phydev->autoneg == AUTONEG_ENABLE) {
> > +		/* Only allow advertising what this PHY supports */
> > +		linkmode_and(phydev->advertising, phydev->advertising,
> > +			     phydev->supported);
> > +		advert = phydev->advertising;
> > +	} else if (phydev->speed < SPEED_1000) {
> >   		return genphy_setup_forced(phydev);
> > +	} else {
> > +		linkmode_zero(fixed_advert);
> > +
> > +		set = phy_lookup_setting(phydev->speed, phydev->duplex,
> > +					 phydev->supported, true);
> > +		if (set)
> > +			linkmode_set(set->bit, fixed_advert);
> > +
> > +		advert = fixed_advert;
> > +	}
> > -	err = genphy_config_advert(phydev);
> > +	err = genphy_config_advert(phydev, advert);
> >   	if (err < 0) /* error */
> >   		return err;
> >   	else if (err)
> 
> It looks great, but I still want to follow Russell's earlier advice and drop
> this patch
> 
> from v14, then submit it separately with the above code.

If the above change is made to phylib, then drivers do not need any
changes other than removing such workarounds detecting !AN with
speed = 1G.

The point of the above change is that drivers shouldn't be doing
anything and the issue should be handled entirely within phylib.

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