e1000e: ensure the link state is correct for serdes links

This patch ensures that the link state (as reported in
mac->serdes_has_link) will transition to false when autoneg fails to
complete but valid codewords were detected.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 48 insertions, 28 deletions

diff --git a/drivers/net/e1000e/82571.c b/drivers/net/e1000e/82571.c
index 26ea5d57a354..227f3d03ba2a 100644
--- a/drivers/net/e1000e/82571.c
+++ b/drivers/net/e1000e/82571.c
@@ -1356,8 +1356,20 @@ static s32 e1000_setup_fiber_serdes_link_82571(struct e1000_hw *hw)
  *  e1000_check_for_serdes_link_82571 - Check for link (Serdes)
  *  @hw: pointer to the HW structure
  *
- *  Checks for link up on the hardware.  If link is not up and we have
- *  a signal, then we need to force link up.
+ *  Reports the link state as up or down.
+ *
+ *  If autonegotiation is supported by the link partner, the link state is
+ *  determined by the result of autonegotiation. This is the most likely case.
+ *  If autonegotiation is not supported by the link partner, and the link
+ *  has a valid signal, force the link up.
+ *
+ *  The link state is represented internally here by 4 states:
+ *
+ *  1) down
+ *  2) autoneg_progress
+ *  3) autoneg_complete (the link sucessfully autonegotiated)
+ *  4) forced_up (the link has been forced up, it did not autonegotiate)
+ *
  **/
 static s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
 {
@@ -1383,6 +1395,7 @@ static s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
                                  */
                                 mac->serdes_link_state =
                                     e1000_serdes_link_autoneg_progress;
+                                mac->serdes_has_link = false;
                                 e_dbg("AN_UP     -> AN_PROG\n");
                         }
                 break;
@@ -1397,57 +1410,64 @@ static s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
                         if (rxcw & E1000_RXCW_C) {
                                 /* Enable autoneg, and unforce link up */
                                 ew32(TXCW, mac->txcw);
-                                ew32(CTRL,
-                                    (ctrl & ~E1000_CTRL_SLU));
+                                ew32(CTRL, (ctrl & ~E1000_CTRL_SLU));
                                 mac->serdes_link_state =
                                     e1000_serdes_link_autoneg_progress;
+                                mac->serdes_has_link = false;
                                 e_dbg("FORCED_UP -> AN_PROG\n");
                         }
                         break;
 
                 case e1000_serdes_link_autoneg_progress:
-                        /*
-                         * If the LU bit is set in the STATUS register,
-                         * autoneg has completed sucessfully. If not,
-                         * try foring the link because the far end may be
-                         * available but not capable of autonegotiation.
-                         */
-                        if (status & E1000_STATUS_LU)  {
-                                mac->serdes_link_state =
-                                    e1000_serdes_link_autoneg_complete;
-                                e_dbg("AN_PROG   -> AN_UP\n");
+                        if (rxcw & E1000_RXCW_C) {
+                                /*
+                                 * We received /C/ ordered sets, meaning the
+                                 * link partner has autonegotiated, and we can
+                                 * trust the Link Up (LU) status bit.
+                                 */
+                                if (status & E1000_STATUS_LU) {
+                                        mac->serdes_link_state =
+                                            e1000_serdes_link_autoneg_complete;
+                                        e_dbg("AN_PROG   -> AN_UP\n");
+                                        mac->serdes_has_link = true;
+                                } else {
+                                        /* Autoneg completed, but failed. */
+                                        mac->serdes_link_state =
+                                            e1000_serdes_link_down;
+                                        e_dbg("AN_PROG   -> DOWN\n");
+                                }
                         } else {
                                 /*
-                                 * Disable autoneg, force link up and
-                                 * full duplex, and change state to forced
+                                 * The link partner did not autoneg.
+                                 * Force link up and full duplex, and change
+                                 * state to forced.
                                  */
-                                ew32(TXCW,
-                                    (mac->txcw & ~E1000_TXCW_ANE));
+                                ew32(TXCW, (mac->txcw & ~E1000_TXCW_ANE));
                                 ctrl |= (E1000_CTRL_SLU | E1000_CTRL_FD);
                                 ew32(CTRL, ctrl);
 
                                 /* Configure Flow Control after link up. */
-                                ret_val =
-                                    e1000e_config_fc_after_link_up(hw);
+                                ret_val = e1000e_config_fc_after_link_up(hw);
                                 if (ret_val) {
                                         e_dbg("Error config flow control\n");
                                         break;
                                 }
                                 mac->serdes_link_state =
                                     e1000_serdes_link_forced_up;
+                                mac->serdes_has_link = true;
                                 e_dbg("AN_PROG   -> FORCED_UP\n");
                         }
-                        mac->serdes_has_link = true;
                         break;
 
                 case e1000_serdes_link_down:
                 default:
-                        /* The link was down but the receiver has now gained
+                        /*
+                         * The link was down but the receiver has now gained
                          * valid sync, so lets see if we can bring the link
-                         * up. */
+                         * up.
+                         */
                         ew32(TXCW, mac->txcw);
-                        ew32(CTRL,
-                            (ctrl & ~E1000_CTRL_SLU));
+                        ew32(CTRL, (ctrl & ~E1000_CTRL_SLU));
                         mac->serdes_link_state =
                             e1000_serdes_link_autoneg_progress;
                         e_dbg("DOWN      -> AN_PROG\n");
@@ -1460,9 +1480,9 @@ static s32 e1000_check_for_serdes_link_82571(struct e1000_hw *hw)
                         e_dbg("ANYSTATE  -> DOWN\n");
                 } else {
                         /*
-                         * We have sync, and can tolerate one
-                         * invalid (IV) codeword before declaring
-                         * link down, so reread to look again
+                         * We have sync, and can tolerate one invalid (IV)
+                         * codeword before declaring link down, so reread
+                         * to look again.
                          */
                         udelay(10);
                         rxcw = er32(RXCW);