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 17:51:04 +0800
From:   Jisheng Zhang <Jisheng.Zhang@...aptics.com>
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, 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

> +       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
>