Re: [RFC PATCH net v2 1/3] net: phy: add an option to disable EEE advertisement

[Anand Moon <linux.amoon-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi Jerome,

On 21 November 2016 at 21:05, Jerome Brunet <jbrunet-rdvid1DuHRBWk0Htik3J/w@public.gmane.org> 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-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>
> ---
>  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 f424b867f73e..a44ee14bd953 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -1348,6 +1348,9 @@ 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_advert_disabled;
> +
>         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 1a4bf8acad78..74c628e046cb 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1116,6 +1116,43 @@ 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 disabled = phydev->eee_advert_disabled;
> +       u32 old_adv, adv;
> +
> +       /* Nothing to disable */
> +       if (!disabled)
> +               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 &= ~disabled;
> +
> +       /* Advertising remains unchanged with the ban */
> +       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
>   *
> @@ -1173,15 +1210,20 @@ 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?
>                  */
> @@ -1191,16 +1233,16 @@ 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);
>
> @@ -1558,6 +1600,21 @@ static void of_set_phy_supported(struct phy_device *phydev)
>                 __set_phy_supported(phydev, max_speed);
>  }
>
> +static void of_set_phy_eee_disable(struct phy_device *phydev)
> +{
> +       struct device_node *node = phydev->mdio.dev.of_node;
> +       u32 disabled;
> +
> +       if (!IS_ENABLED(CONFIG_OF_MDIO))
> +               return;
> +
> +       if (!node)
> +               return;
> +
> +       if (!of_property_read_u32(node, "eee-advert-disable", &disabled))
> +               phydev->eee_advert_disabled = disabled;
> +}
> +
>  /**
>   * phy_probe - probe and init a PHY device
>   * @dev: device to probe and init
> @@ -1595,6 +1652,11 @@ 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_disable(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 e25f1830fbcf..7f2ea0af16d1 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -401,6 +401,9 @@ struct phy_device {
>         u32 advertising;
>         u32 lp_advertising;
>
> +       /* Energy efficient ethernet modes which should be prohibited */
> +       u32 eee_advert_disabled;
> +
>         int autoneg;
>
>         int link_timeout;
> --
> 2.7.4
>

iperf3 tcp test summary at my end

Test Complete. Summary Results:
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-100.00 sec  10.9 GBytes   936 Mbits/sec    0             sender
[  4]   0.00-100.00 sec  10.9 GBytes   936 Mbits/sec                  receiver
CPU Utilization: local/sender 5.7% (0.2%u/5.5%s), remote/receiver
11.9% (0.9%u/11.0%s)

iperf3 udp test summary at my end.

Test Complete. Summary Results:
[ ID] Interval           Transfer     Bandwidth       Jitter
Lost/Total Datagrams
[  4]   0.00-100.00 sec  12.5 MBytes  1.05 Mbits/sec  0.025 ms  0/1599 (0%)
[  4] Sent 1599 datagrams
CPU Utilization: local/sender 0.1% (0.0%u/0.1%s), remote/receiver 0.0%
(0.0%u/0.0%s)

Best Regards
-Anand Moon
>
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