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