Re: [PATCH net-next v3 1/4] net: phy: add an option to disable EEE advertisement

[Yegor Yefremov]

On Mon, Nov 28, 2016 at 10:46 AM, Jerome Brunet <jbrunet@xxxxxxxxxxxx> wrote:
> This patch adds an option to disable EEE advertisement in the generic PHY
> by providing a mask of prohibited modes corresponding to the value found in
> the MDIO_AN_EEE_ADV register.
>
> On some platforms, PHY Low power idle seems to be causing issues, even
> breaking the link some cases. The patch provides a convenient way for these
> platforms to disable EEE advertisement and work around the issue.
>
> Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>

Tested using Baltos ir2110 device (cpsw + at8035 PHY).

Tested-by: Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>

> ---
>  drivers/net/phy/phy.c        |  3 ++
>  drivers/net/phy/phy_device.c | 80 +++++++++++++++++++++++++++++++++++++++-----
>  include/linux/phy.h          |  3 ++
>  3 files changed, 77 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 73adbaa9ac86..a3981cc6448a 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -1396,6 +1396,9 @@ int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
>  {
>         int val = ethtool_adv_to_mmd_eee_adv_t(data->advertised);
>
> +       /* Mask prohibited EEE modes */
> +       val &= ~phydev->eee_broken_modes;
> +
>         phy_write_mmd_indirect(phydev, MDIO_AN_EEE_ADV, MDIO_MMD_AN, val);
>
>         return 0;
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index ba86c191a13e..83e52f1b80f2 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1121,6 +1121,43 @@ static int genphy_config_advert(struct phy_device *phydev)
>  }
>
>  /**
> + * genphy_config_eee_advert - disable unwanted eee mode advertisement
> + * @phydev: target phy_device struct
> + *
> + * Description: Writes MDIO_AN_EEE_ADV after disabling unsupported energy
> + *   efficent ethernet modes. Returns 0 if the PHY's advertisement hasn't
> + *   changed, and 1 if it has changed.
> + */
> +static int genphy_config_eee_advert(struct phy_device *phydev)
> +{
> +       u32 broken = phydev->eee_broken_modes;
> +       u32 old_adv, adv;
> +
> +       /* Nothing to disable */
> +       if (!broken)
> +               return 0;
> +
> +       /* If the following call fails, we assume that EEE is not
> +        * supported by the phy. If we read 0, EEE is not advertised
> +        * In both case, we don't need to continue
> +        */
> +       adv = phy_read_mmd_indirect(phydev, MDIO_AN_EEE_ADV, MDIO_MMD_AN);
> +       if (adv <= 0)
> +               return 0;
> +
> +       old_adv = adv;
> +       adv &= ~broken;
> +
> +       /* Advertising remains unchanged with the broken mask */
> +       if (old_adv == adv)
> +               return 0;
> +
> +       phy_write_mmd_indirect(phydev, MDIO_AN_EEE_ADV, MDIO_MMD_AN, adv);
> +
> +       return 1;
> +}
> +
> +/**
>   * genphy_setup_forced - configures/forces speed/duplex from @phydev
>   * @phydev: target phy_device struct
>   *
> @@ -1178,15 +1215,20 @@ EXPORT_SYMBOL(genphy_restart_aneg);
>   */
>  int genphy_config_aneg(struct phy_device *phydev)
>  {
> -       int result;
> +       int err, changed;
> +
> +       changed = genphy_config_eee_advert(phydev);
>
>         if (AUTONEG_ENABLE != phydev->autoneg)
>                 return genphy_setup_forced(phydev);
>
> -       result = genphy_config_advert(phydev);
> -       if (result < 0) /* error */
> -               return result;
> -       if (result == 0) {
> +       err = genphy_config_advert(phydev);
> +       if (err < 0) /* error */
> +               return err;
> +
> +       changed |= err;
> +
> +       if (changed == 0) {
>                 /* Advertisement hasn't changed, but maybe aneg was never on to
>                  * begin with?  Or maybe phy was isolated?
>                  */
> @@ -1196,16 +1238,16 @@ int genphy_config_aneg(struct phy_device *phydev)
>                         return ctl;
>
>                 if (!(ctl & BMCR_ANENABLE) || (ctl & BMCR_ISOLATE))
> -                       result = 1; /* do restart aneg */
> +                       changed = 1; /* do restart aneg */
>         }
>
>         /* Only restart aneg if we are advertising something different
>          * than we were before.
>          */
> -       if (result > 0)
> -               result = genphy_restart_aneg(phydev);
> +       if (changed > 0)
> +               return genphy_restart_aneg(phydev);
>
> -       return result;
> +       return 0;
>  }
>  EXPORT_SYMBOL(genphy_config_aneg);
>
> @@ -1563,6 +1605,21 @@ static void of_set_phy_supported(struct phy_device *phydev)
>                 __set_phy_supported(phydev, max_speed);
>  }
>
> +static void of_set_phy_eee_broken(struct phy_device *phydev)
> +{
> +       struct device_node *node = phydev->mdio.dev.of_node;
> +       u32 broken;
> +
> +       if (!IS_ENABLED(CONFIG_OF_MDIO))
> +               return;
> +
> +       if (!node)
> +               return;
> +
> +       if (!of_property_read_u32(node, "eee-broken-modes", &broken))
> +               phydev->eee_broken_modes = broken;
> +}
> +
>  /**
>   * phy_probe - probe and init a PHY device
>   * @dev: device to probe and init
> @@ -1600,6 +1657,11 @@ static int phy_probe(struct device *dev)
>         of_set_phy_supported(phydev);
>         phydev->advertising = phydev->supported;
>
> +       /* Get the EEE modes we want to prohibit. We will ask
> +        * the PHY stop advertising these mode later on
> +        */
> +       of_set_phy_eee_broken(phydev);
> +
>         /* Set the state to READY by default */
>         phydev->state = PHY_READY;
>
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index edde28ce163a..b53177fd38af 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -417,6 +417,9 @@ struct phy_device {
>         u32 advertising;
>         u32 lp_advertising;
>
> +       /* Energy efficient ethernet modes which should be prohibited */
> +       u32 eee_broken_modes;
> +
>         int autoneg;
>
>         int link_timeout;
> --
> 2.7.4
>