linux-kernel - Re: [PATCH] net: phy: marvell: Fix RGMII Tx/Rx delays setting in 88e1121-compatible PHYs

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Date:   Fri, 4 Feb 2022 10:41:37 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Пархоменко Павел Кириллович <Pavel.Parkhomenko@...kalelectronics.ru>,
        "michael@...pelberg.de" <michael@...pelberg.de>,
        "afleming@...il.com" <afleming@...il.com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "andrew@...n.ch" <andrew@...n.ch>,
        Малахов Алексей Валерьевич <Alexey.Malahov@...kalelectronics.ru>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Serge Semin <fancer.lancer@...il.com>
Subject: Re: [PATCH] net: phy: marvell: Fix RGMII Tx/Rx delays setting in
 88e1121-compatible PHYs

On Fri, Feb 04, 2022 at 12:56:21PM +0300, Serge Semin wrote:
> +Cc: Heiner, Russel, David, Jakub
> 
> -Sergey
> 
> On Fri, Feb 04, 2022 at 08:29:11AM +0300, Пархоменко Павел Кириллович wrote:
> > It is mandatory for a software to issue a reset upon modifying RGMII
> > Receive Timing Control and RGMII Transmit Timing Control bit fields of MAC
> > Specific Control register 2 (page 2, register 21) otherwise the changes
> > won't be perceived by the PHY (the same is applicable for a lot of other
> > registers). Not setting the RGMII delays on the platforms that imply
> > it's being done on the PHY side will consequently cause the traffic loss.
> > We discovered that the denoted soft-reset is missing in the
> > m88e1121_config_aneg() method for the case if the RGMII delays are
> > modified but the MDIx polarity isn't changed or the auto-negotiation is
> > left enabled, thus causing the traffic loss on our platform with Marvell
> > Alaska 88E1510 installed. Let's fix that by issuing the soft-reset if the
> > delays have been actually set in the m88e1121_config_aneg_rgmii_delays()
> > method.

Thanks. Indeed, this appears to be correct for the 88E151x PHYs.

Reviewed-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

> > Fixes: d6ab93364734 ("net: phy: marvell: Avoid unnecessary soft reset")
> > Signed-off-by: Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>
> > Reviewed-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> > Cc: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
> > Cc: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> > Cc: netdev@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > 
> > ---
> >  drivers/net/phy/marvell.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
> > index 4fcfca4e1702..a4f685927a64 100644
> > --- a/drivers/net/phy/marvell.c
> > +++ b/drivers/net/phy/marvell.c
> > @@ -551,9 +551,9 @@ static int m88e1121_config_aneg_rgmii_delays(struct
> > phy_device *phydev)
> >  	else
> >  		mscr = 0;
> >  
> > -	return phy_modify_paged(phydev, MII_MARVELL_MSCR_PAGE,
> > -				MII_88E1121_PHY_MSCR_REG,
> > -				MII_88E1121_PHY_MSCR_DELAY_MASK, mscr);
> > +	return phy_modify_paged_changed(phydev, MII_MARVELL_MSCR_PAGE,
> > +					MII_88E1121_PHY_MSCR_REG,
> > +					MII_88E1121_PHY_MSCR_DELAY_MASK, mscr);
> >  }
> >  
> >  static int m88e1121_config_aneg(struct phy_device *phydev)
> > @@ -567,11 +567,13 @@ static int m88e1121_config_aneg(struct phy_device *phydev)
> >  			return err;
> >  	}
> >  
> > +	changed = err;
> > +
> >  	err = marvell_set_polarity(phydev, phydev->mdix_ctrl);
> >  	if (err < 0)
> >  		return err;
> >  
> > -	changed = err;
> > +	changed |= err;
> >  
> >  	err = genphy_config_aneg(phydev);
> >  	if (err < 0)
> > -- 
> > 2.34.1
> > 
> > 
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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