ixgbevf: introduce delay for checking VFLINKS on 82599

VFLINKS.LINKUP bit tends to flap when a DA or SFP+ cable is disconnected.
It can take up to 500 usecs for the LINKUP bit to be correct.

This patch resolves the issue by introducing a delay for 82599 VFs of at
least 500 usecs to make sure the VFLINKS value is correct.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/ixgbevf/vf.c b/drivers/net/ethernet/intel/ixgbevf/vf.c
index 4d44d64..9cddd56 100644 (file)
--- a/drivers/net/ethernet/intel/ixgbevf/vf.c
+++ b/drivers/net/ethernet/intel/ixgbevf/vf.c
@@ -434,6 +434,21 @@ static s32 ixgbevf_check_mac_link_vf(struct ixgbe_hw *hw,
        if (!(links_reg & IXGBE_LINKS_UP))
                goto out;
 
+       /* for SFP+ modules and DA cables on 82599 it can take up to 500usecs
+        * before the link status is correct
+        */
+       if (mac->type == ixgbe_mac_82599_vf) {
+               int i;
+
+               for (i = 0; i < 5; i++) {
+                       udelay(100);
+                       links_reg = IXGBE_READ_REG(hw, IXGBE_VFLINKS);
+
+                       if (!(links_reg & IXGBE_LINKS_UP))
+                               goto out;
+               }
+       }
+
        switch (links_reg & IXGBE_LINKS_SPEED_82599) {
        case IXGBE_LINKS_SPEED_10G_82599:
                *speed = IXGBE_LINK_SPEED_10GB_FULL;