6.3-RELEASE/7.0-RC1: em(4) fails on 82571EB_SERDES

[Patrick Oeschger]

maybe i found two issues which are em(4) related...
i tested the 6.3-RELEASE on a appliance which has two on-board SFP slots
chipset: i82571eb (serdes with tbi-interface)
em4 at pci8:0:0:   class=0x020000 card=0x10761903 chip=0x10608086 rev=0x06 hdr=0x00
em5 at pci8:0:1:   class=0x020000 card=0x10761903 chip=0x10608086 rev=0x06 hdr=0x00

first issue:
on the SFP ports link status is always up - even if no fiber optic cable is
attached
this problem seems to be E1000_STATUS_LU related (in serdes mode the chipset
will use the LU flag to indicate 'signal loss' which it gets signaled from the
SFP module
- PCIe* Gbe Controllers Open Source Software Developer's Manual
  DocID: 316080-001 (December 2006)
   8.3.3    Loss of Signal/Link Status Indication
  14.8.3    Mac/SerDes (TBI-Mode) Link Setup
the following patch resolved this issue during my test:

--- sys/dev/em/if_em.c.orig     2008-01-22 16:55:06.000000000 +0100
+++ sys/dev/em/if_em.c  2008-01-22 13:33:58.000000000 +0100
@@ -2491,9 +2494,21 @@
 {
        struct ifnet *ifp = adapter->ifp;
        device_t dev = adapter->dev;
+       bool status_lu = E1000_READ_REG(&adapter->hw, E1000_STATUS) &
+                         E1000_STATUS_LU;
+
+       if ((adapter->hw.device_id == E1000_DEV_ID_82571EB_SERDES) &&
+            (!(E1000_READ_REG(&adapter->hw, E1000_TXCW) & E1000_TXCW_ANE)) &&
+           (E1000_READ_REG(&adapter->hw, E1000_CTRL) & E1000_CTRL_SLU)) {
+               if (E1000_READ_REG(&adapter->hw, E1000_STATUS) &
+                   E1000_STATUS_LU) {
+                       status_lu = 0;
+               } else {
+                       status_lu = 1;
+               }
+       }
 
-       if (E1000_READ_REG(&adapter->hw, E1000_STATUS) &
-           E1000_STATUS_LU) {
+       if (status_lu) {
                if (adapter->link_active == 0) {
                        e1000_get_speed_and_duplex(&adapter->hw, 
                            &adapter->link_speed, &adapter->link_duplex);

second issue:
during branching of the fibre optic cabling i get a few messages regarding
'coalesced states'
Jan 22 10:36:00 test kernel: em4: 2 link states coalesced
this seems to be because of link state interrupts generated by the chipset
during branching of the fiber optic cable the link can change quickly
multiple times
the following patch resolved this issue during my test:
...maybe the driver needs the same for EM_FAST_IRQ and POLLING(?)

--- sys/dev/em/if_em.c.orig     2008-01-22 16:55:06.000000000 +0100
+++ sys/dev/em/if_em.c  2008-01-22 13:33:58.000000000 +0100
@@ -1460,7 +1460,9 @@
        struct adapter  *adapter = arg;
        struct ifnet    *ifp;
        uint32_t        reg_icr;
-
+       bool            do_update = (adapter->hw.device_id == 
+                                    E1000_DEV_ID_82571EB_SERDES) ?
+                                    FALSE : TRUE;
        EM_CORE_LOCK(adapter);
        ifp = adapter->ifp;
 
@@ -1499,7 +1501,8 @@
                        callout_stop(&adapter->timer);
                        adapter->hw.mac.get_link_status = 1;
                        e1000_check_for_link(&adapter->hw);
-                       em_update_link_status(adapter);
+                       if (do_update)
+                               em_update_link_status(adapter);
                        /* Deal with TX cruft when link lost */
                        em_tx_purge(adapter);
                        callout_reset(&adapter->timer, hz,

- is there any way to get 82571_SERDES working in a future release of the
  em(4) driver?

input on this issue is very welcome
br
-pat-