netdev - Re: [PATCH v2] net: phy: marvell: Fix pause frame negotiation

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Message-ID: <20200411165029.694a1b8b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Sat, 11 Apr 2020 16:50:29 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     Clemens Gruber <clemens.gruber@...ruber.com>,
        netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: phy: marvell: Fix pause frame negotiation

On Sun, 12 Apr 2020 00:45:59 +0100 Russell King - ARM Linux admin wrote:
> On Sat, Apr 11, 2020 at 04:28:24PM -0700, Jakub Kicinski wrote:
> > On Sat, 11 Apr 2020 18:51:25 +0200 Clemens Gruber wrote:  
> > > The negotiation of flow control / pause frame modes was broken since
> > > commit fcf1f59afc67 ("net: phy: marvell: rearrange to use
> > > genphy_read_lpa()") moved the setting of phydev->duplex below the
> > > phy_resolve_aneg_pause call. Due to a check of DUPLEX_FULL in that
> > > function, phydev->pause was no longer set.
> > > 
> > > Fix it by moving the parsing of the status variable before the blocks
> > > dealing with the pause frames.
> > > 
> > > As the Marvell 88E1510 datasheet does not specify the timing between the
> > > link status and the "Speed and Duplex Resolved" bit, we have to force
> > > the link down as long as the resolved bit is not set, to avoid reporting
> > > link up before we even have valid Speed/Duplex.
> > > 
> > > Tested with a Marvell 88E1510 (RGMII to Copper/1000Base-T)
> > > 
> > > Fixes: fcf1f59afc67 ("net: phy: marvell: rearrange to use genphy_read_lpa()")
> > > Signed-off-by: Clemens Gruber <clemens.gruber@...ruber.com>
> > > ---
> > > Changes since v1:
> > > - Force link to 0 if resolved bit is not set as suggested by Russell King
> > > 
> > >  drivers/net/phy/marvell.c | 46 ++++++++++++++++++++-------------------
> > >  1 file changed, 24 insertions(+), 22 deletions(-)
> > > 
> > > diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
> > > index 9a8badafea8a..561df5e33f65 100644
> > > --- a/drivers/net/phy/marvell.c
> > > +++ b/drivers/net/phy/marvell.c
> > > @@ -1278,6 +1278,30 @@ static int marvell_read_status_page_an(struct phy_device *phydev,
> > >  	int lpa;
> > >  	int err;
> > >  
> > > +	if (!(status & MII_M1011_PHY_STATUS_RESOLVED)) {
> > > +		phydev->link = 0;
> > > +		return 0;
> > > +	}  
> > 
> > This doesn't address my comment, so was I wrong? What I was trying to
> > say is that the function updates the established link info as well as
> > autoneg advertising info. If the link is not resolved we can't read the
> > link info, but we should still report the advertising modes. No?  
> 
> If we report that the link is down, then the advertising modes are
> irrelevent.

Ugh, these are link partner modes...

Applied, thanks!