phylib EEE updates

David,

This series of patches depends on the previous set of changes, and is therefore net-next material.

While testing the EEE code, I discovered a number of issues:

1. It is possible to enable advertisment of EEE modes which are not supported by the hardware. We omit to check the supported modes and mask off those modes that are not supported before writing the EEE advertisment register.

2. We need to restart autonegotiation after a change of the EEE advertisment, otherwise the link partner does not see the updated EEE modes.

3. SGMII connected PHYs are also capable of supporting EEE.

Through discussion with Florian, it has been decided to remove the check for the PHY interface mode in patch (3).

 drivers/net/phy/phy.c | 37 ++++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

v2: fix "phy_restart_aneg" build error identified by 0-day
v3: drop RFC tag, replace 3rd patch

RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

We currently allow userspace to set any EEE advertisments it desires, whether or not the PHY supports them. For example:

 # ethtool --set-eee eth1 advertise 0xffffffff
 # ethtool --show-eee eth1
 EEE Settings for eth1:
        EEE status: disabled
        Tx LPI: disabled
        Supported EEE link modes:  100baseT/Full
                                   1000baseT/Full
                                   10000baseT/Full
        Advertised EEE link modes:  100baseT/Full
                                    1000baseT/Full
                                    1000baseKX/Full
                                    10000baseT/Full
                                    10000baseKX4/Full
                                    10000baseKR/Full

Clearly, this is not sane, we should only allow link modes that are supported to be advertised (as we do elsewhere.) Ensure that we mask the MDIO_AN_EEE_ADV value with the capabilities retrieved from the MDIO_PCS_EEE_ABLE register.

---
 drivers/net/phy/phy.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

index ba4676ee9018..7b1c93b0233a 100644
@@ -1332,17 +1332,22 @@ EXPORT_SYMBOL(phy_ethtool_get_eee);
  */
 int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
 {
-	int val = ethtool_adv_to_mmd_eee_adv_t(data->advertised);
+	int cap, adv;
 
 	if (!phydev->drv)
 		return -EIO;
 
-	/* Mask prohibited EEE modes */
-	val &= ~phydev->eee_broken_modes;
+	/* Get Supported EEE */
+	cap = phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_PCS_EEE_ABLE);
+	if (cap < 0)
+		return cap;
 
-	phy_write_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_ADV, val);
+	adv = ethtool_adv_to_mmd_eee_adv_t(data->advertised) & cap;
 
-	return 0;
+	/* Mask prohibited EEE modes */
+	adv &= ~phydev->eee_broken_modes;
+
+	return phy_write_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_ADV, adv);
 }
 EXPORT_SYMBOL(phy_ethtool_set_eee);
 

2.7.4

When the EEE advertisment is changed, we should restart autonegotiation to update the link partner with the new EEE settings. Add this trigger but only if the advertisment has changed.

---
 drivers/net/phy/phy.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

index 7b1c93b0233a..345251f21699 100644
@@ -1332,7 +1332,7 @@ EXPORT_SYMBOL(phy_ethtool_get_eee);
  */
 int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
 {
-	int cap, adv;
+	int cap, old_adv, adv, ret;
 
 	if (!phydev->drv)
 		return -EIO;

@@ -1342,12 +1342,29 @@ int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
 	if (cap < 0)
 		return cap;
 
+	old_adv = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_ADV);
+	if (old_adv < 0)
+		return old_adv;
+
 	adv = ethtool_adv_to_mmd_eee_adv_t(data->advertised) & cap;
 
 	/* Mask prohibited EEE modes */
 	adv &= ~phydev->eee_broken_modes;
 
-	return phy_write_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_ADV, adv);
+	if (old_adv != adv) {
+		ret = phy_write_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_ADV, adv);
+		if (ret < 0)
+			return ret;
+
+		/* Restart autonegotiation so the new modes get sent to the
+		 * link partner.
+		 */
+		ret = genphy_restart_aneg(phydev);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
 }
 EXPORT_SYMBOL(phy_ethtool_set_eee);
 

2.7.4

EEE is able to work in any PHY interface mode, there is nothing which fundamentally restricts it to only a few modes. For example, EEE works in SGMII mode with the Marvell 88E1512.

Rather than just adding SGMII mode to the list, Florian suggests removing the list of interface modes entirely:

It actually sounds like we should just kill the check entirely, it does not appear that any of the interface mode would not fundamentally be able to support EEE, because the "lowest" mode we support is MII, and even there it's quite possible to support EEE.

---
 drivers/net/phy/phy.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

index 345251f21699..867c42154087 100644
@@ -1208,15 +1208,8 @@ int phy_init_eee(struct phy_device *phydev, bool clk_stop_enable)
 		return -EIO;
 
 	/* According to 802.3az,the EEE is supported only in full duplex-mode.
-	 * Also EEE feature is active when core is operating with MII, GMII
-	 * or RGMII (all kinds). Internal PHYs are also allowed to proceed and
-	 * should return an error if they do not support EEE.
 	 */
-	if ((phydev->duplex == DUPLEX_FULL) &&
-	    ((phydev->interface == PHY_INTERFACE_MODE_MII) ||
-	    (phydev->interface == PHY_INTERFACE_MODE_GMII) ||
-	     phy_interface_is_rgmii(phydev) ||
-	     phy_is_internal(phydev))) {
+	if (phydev->duplex == DUPLEX_FULL) {
 		int eee_lp, eee_cap, eee_adv;
 		u32 lp, cap, adv;
 		int status;

2.7.4

From: Russell King - ARM Linux <[email protected]>
Date: Fri, 31 Mar 2017 10:36:46 +0100

Series applied, thank you.