netdev - Re: [EXT] Re: Phylink flow control support on ports with MLO_AN

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Date:   Sat, 13 Feb 2021 11:39:47 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Stefan Chulski <stefanc@...vell.com>
Cc:     "andrew@...n.ch" <andrew@...n.ch>,
        Jakub Kicinski <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Marcin Wojtas (mw@...ihalf.com)" <mw@...ihalf.com>,
        Nadav Haklai <nadavh@...vell.com>,
        Yan Markman <ymarkman@...vell.com>
Subject: Re: [EXT] Re: Phylink flow control support on ports with
 MLO_AN_FIXED auto negotiation

On Sun, Jan 31, 2021 at 12:19:50PM +0000, Russell King - ARM Linux admin wrote:
> On Sun, Jan 31, 2021 at 11:12:14AM +0000, Russell King - ARM Linux admin wrote:
> > I discussed it with Andrew earlier last year, and his response was:
> > 
> >  DT configuration of pause for fixed link probably is sufficient. I don't
> >  remember it ever been really discussed for DSA. It was a Melanox
> >  discussion about limiting pause for the CPU. So I think it is safe to
> >  not implement ethtool -A, at least until somebody has a real use case
> >  for it.
> > 
> > So I chose not to support it - no point supporting features that people
> > aren't using. If you have a "real use case" then it can be added.
> 
> This patch may be sufficient - I haven't fully considered all the
> implications of changing this though.

Did you try this patch? What's the outcome?

> 
>  drivers/net/phy/phylink.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
> index 7e0fdc17c8ee..2ee0d4dcf9a5 100644
> --- a/drivers/net/phy/phylink.c
> +++ b/drivers/net/phy/phylink.c
> @@ -673,7 +673,6 @@ static void phylink_resolve(struct work_struct *w)
>  		switch (pl->cur_link_an_mode) {
>  		case MLO_AN_PHY:
>  			link_state = pl->phy_state;
> -			phylink_apply_manual_flow(pl, &link_state);
>  			mac_config = link_state.link;
>  			break;
>  
> @@ -698,11 +697,12 @@ static void phylink_resolve(struct work_struct *w)
>  				link_state.pause = pl->phy_state.pause;
>  				mac_config = true;
>  			}
> -			phylink_apply_manual_flow(pl, &link_state);
>  			break;
>  		}
>  	}
>  
> +	phylink_apply_manual_flow(pl, &link_state);
> +
>  	if (mac_config) {
>  		if (link_state.interface != pl->link_config.interface) {
>  			/* The interface has changed, force the link down and
> @@ -1639,9 +1639,6 @@ int phylink_ethtool_set_pauseparam(struct phylink *pl,
>  
>  	ASSERT_RTNL();
>  
> -	if (pl->cur_link_an_mode == MLO_AN_FIXED)
> -		return -EOPNOTSUPP;
> -
>  	if (!phylink_test(pl->supported, Pause) &&
>  	    !phylink_test(pl->supported, Asym_Pause))
>  		return -EOPNOTSUPP;
> @@ -1684,7 +1681,7 @@ int phylink_ethtool_set_pauseparam(struct phylink *pl,
>  	/* Update our in-band advertisement, triggering a renegotiation if
>  	 * the advertisement changed.
>  	 */
> -	if (!pl->phydev)
> +	if (!pl->phydev && pl->cur_link_an_mode != MLO_AN_FIXED)
>  		phylink_change_inband_advert(pl);
>  
>  	mutex_unlock(&pl->state_mutex);
> 
> -- 
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!