net: add linkmode helper for setting flow control advertisement

Add a linkmode helper to set the flow control advertisement in an
ethtool linkmode mask according to the tx/rx capabilities. This
implementation is moved from phylib, and documented with an
analysis of its shortcomings.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/linkmode.c b/drivers/net/phy/linkmode.c
index 9699187..f60560f 100644 (file)
--- a/drivers/net/phy/linkmode.c
+++ b/drivers/net/phy/linkmode.c
@@ -42,3 +42,54 @@ void linkmode_resolve_pause(const unsigned long *local_adv,
        }
 }
 EXPORT_SYMBOL_GPL(linkmode_resolve_pause);
+
+/**
+ * linkmode_set_pause - set the pause mode advertisement
+ * @advertisement: advertisement in ethtool format
+ * @tx: boolean from ethtool struct ethtool_pauseparam tx_pause member
+ * @rx: boolean from ethtool struct ethtool_pauseparam rx_pause member
+ *
+ * Configure the advertised Pause and Asym_Pause bits according to the
+ * capabilities of provided in @tx and @rx.
+ *
+ * We convert as follows:
+ *  tx rx  Pause AsymDir
+ *  0  0   0     0
+ *  0  1   1     1
+ *  1  0   0     1
+ *  1  1   1     0
+ *
+ * Note: this translation from ethtool tx/rx notation to the advertisement
+ * is actually very problematical. Here are some examples:
+ *
+ * For tx=0 rx=1, meaning transmit is unsupported, receive is supported:
+ *
+ *  Local device  Link partner
+ *  Pause AsymDir Pause AsymDir Result
+ *    1     1       1     0     TX + RX - but we have no TX support.
+ *    1     1       0     1    Only this gives RX only
+ *
+ * For tx=1 rx=1, meaning we have the capability to transmit and receive
+ * pause frames:
+ *
+ *  Local device  Link partner
+ *  Pause AsymDir Pause AsymDir Result
+ *    1     0       0     1     Disabled - but since we do support tx and rx,
+ *                             this should resolve to RX only.
+ *
+ * Hence, asking for:
+ *  rx=1 tx=0 gives Pause+AsymDir advertisement, but we may end up
+ *            resolving to tx+rx pause or only rx pause depending on
+ *            the partners advertisement.
+ *  rx=0 tx=1 gives AsymDir only, which will only give tx pause if
+ *            the partners advertisement allows it.
+ *  rx=1 tx=1 gives Pause only, which will only allow tx+rx pause
+ *            if the other end also advertises Pause.
+ */
+void linkmode_set_pause(unsigned long *advertisement, bool tx, bool rx)
+{
+       linkmode_mod_bit(ETHTOOL_LINK_MODE_Pause_BIT, advertisement, rx);
+       linkmode_mod_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, advertisement,
+                        rx ^ tx);
+}
+EXPORT_SYMBOL_GPL(linkmode_set_pause);

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index f5a7a07..2a97326 100644 (file)
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2361,22 +2361,7 @@ void phy_set_asym_pause(struct phy_device *phydev, bool rx, bool tx)
        __ETHTOOL_DECLARE_LINK_MODE_MASK(oldadv);
 
        linkmode_copy(oldadv, phydev->advertising);
-
-       linkmode_clear_bit(ETHTOOL_LINK_MODE_Pause_BIT,
-                          phydev->advertising);
-       linkmode_clear_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT,
-                          phydev->advertising);
-
-       if (rx) {
-               linkmode_set_bit(ETHTOOL_LINK_MODE_Pause_BIT,
-                                phydev->advertising);
-               linkmode_set_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT,
-                                phydev->advertising);
-       }
-
-       if (tx)
-               linkmode_change_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT,
-                                   phydev->advertising);
+       linkmode_set_pause(phydev->advertising, tx, rx);
 
        if (!linkmode_equal(oldadv, phydev->advertising) &&
            phydev->autoneg)

diff --git a/include/linux/linkmode.h b/include/linux/linkmode.h
index 9ec210f..c664c27 100644 (file)
--- a/include/linux/linkmode.h
+++ b/include/linux/linkmode.h
@@ -92,4 +92,6 @@ void linkmode_resolve_pause(const unsigned long *local_adv,
                            const unsigned long *partner_adv,
                            bool *tx_pause, bool *rx_pause);
 
+void linkmode_set_pause(unsigned long *advertisement, bool tx, bool rx);
+
 #endif /* __LINKMODE_H */