linux-kernel - RE: [PATCH V3 net-next 3/4] net: phy: realtek: add dt property to enable ALDPS mode

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Date:   Tue, 8 Jun 2021 10:14:40 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     Jisheng Zhang <Jisheng.Zhang@...aptics.com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH V3 net-next 3/4] net: phy: realtek: add dt property to
 enable ALDPS mode


Hi Jisheng,

> -----Original Message-----
> From: Jisheng Zhang <Jisheng.Zhang@...aptics.com>
> Sent: 2021年6月8日 17:51
> To: Joakim Zhang <qiangqing.zhang@....com>
> Cc: davem@...emloft.net; kuba@...nel.org; robh+dt@...nel.org;
> andrew@...n.ch; hkallweit1@...il.com; linux@...linux.org.uk;
> f.fainelli@...il.com; dl-linux-imx <linux-imx@....com>;
> netdev@...r.kernel.org; devicetree@...r.kernel.org;
> linux-kernel@...r.kernel.org
> Subject: Re: [PATCH V3 net-next 3/4] net: phy: realtek: add dt property to
> enable ALDPS mode
> 
> On Tue,  8 Jun 2021 11:15:34 +0800
> Joakim Zhang <qiangqing.zhang@....com> wrote:
> 
> 
> >
> >
> > If enable Advance Link Down Power Saving (ALDPS) mode, it will change
> > crystal/clock behavior, which cause RXC clock stop for dozens to
> > hundreds of miliseconds. This is comfirmed by Realtek engineer. For
> > some MACs, it needs RXC clock to support RX logic, after this patch,
> > PHY can generate continuous RXC clock during auto-negotiation.
> >
> > ALDPS default is disabled after hardware reset, it's more reasonable
> > to add a property to enable this feature, since ALDPS would introduce side
> effect.
> > This patch adds dt property "realtek,aldps-enable" to enable ALDPS
> > mode per users' requirement.
> >
> > Jisheng Zhang enables this feature, changes the default behavior.
> > Since mine patch breaks the rule that new implementation should not
> > break existing design, so Cc'ed let him know to see if it can be accepted.
> >
> > Cc: Jisheng Zhang <Jisheng.Zhang@...aptics.com>
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> > ---
> >  drivers/net/phy/realtek.c | 20 +++++++++++++++++---
> >  1 file changed, 17 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
> > index ca258f2a9613..79dc55bb4091 100644
> > --- a/drivers/net/phy/realtek.c
> > +++ b/drivers/net/phy/realtek.c
> > @@ -76,6 +76,7 @@ MODULE_AUTHOR("Johnson Leung");
> > MODULE_LICENSE("GPL");
> >
> >  struct rtl821x_priv {
> > +       u16 phycr1;
> >         u16 phycr2;
> >  };
> >
> > @@ -98,6 +99,14 @@ static int rtl821x_probe(struct phy_device *phydev)
> >         if (!priv)
> >                 return -ENOMEM;
> >
> > +       priv->phycr1 = phy_read_paged(phydev, 0xa43,
> RTL8211F_PHYCR1);
> > +       if (priv->phycr1 < 0)
> > +               return priv->phycr1;
> > +
> > +       priv->phycr1 &= (RTL8211F_ALDPS_PLL_OFF |
> > + RTL8211F_ALDPS_ENABLE | RTL8211F_ALDPS_XTAL_OFF);
> 
> priv->phycr1 is 0 by default, so above 5 LoCs can be removed

The intention of this is to take bootloader into account. Such as uboot configure the PHY before.

Best Regards,
Joakim Zhang
> > +       if (of_property_read_bool(dev->of_node, "realtek,aldps-enable"))
> > +               priv->phycr1 |= RTL8211F_ALDPS_PLL_OFF |
> > + RTL8211F_ALDPS_ENABLE | RTL8211F_ALDPS_XTAL_OFF;
> > +
> >         priv->phycr2 = phy_read_paged(phydev, 0xa43,
> RTL8211F_PHYCR2);
> >         if (priv->phycr2 < 0)
> >                 return priv->phycr2;
> > @@ -324,11 +333,16 @@ static int rtl8211f_config_init(struct phy_device
> *phydev)
> >         struct rtl821x_priv *priv = phydev->priv;
> >         struct device *dev = &phydev->mdio.dev;
> >         u16 val_txdly, val_rxdly;
> > -       u16 val;
> >         int ret;
> >
> > -       val = RTL8211F_ALDPS_ENABLE | RTL8211F_ALDPS_PLL_OFF |
> RTL8211F_ALDPS_XTAL_OFF;
> > -       phy_modify_paged_changed(phydev, 0xa43, RTL8211F_PHYCR1, val,
> val);
> > +       ret = phy_modify_paged_changed(phydev, 0xa43,
> RTL8211F_PHYCR1,
> > +                                      RTL8211F_ALDPS_PLL_OFF |
> RTL8211F_ALDPS_ENABLE | RTL8211F_ALDPS_XTAL_OFF,
> > +                                      priv->phycr1);
> > +       if (ret < 0) {
> > +               dev_err(dev, "aldps mode  configuration failed: %pe\n",
> > +                       ERR_PTR(ret));
> > +               return ret;
> > +       }
> >
> >         switch (phydev->interface) {
> >         case PHY_INTERFACE_MODE_RGMII:
> > --
> > 2.17.1
> >