e1000e: perform 10/100 adaptive IFS only on parts that support it

Adaptive IFS which involves writing to the Adaptive IFS Throttle register
was being done for all devices supported by the driver even though it is
not supported (i.e. the register doesn't even exist) on some devices.  The
feature is supported on 8257x/82583 and ICH/PCH based devices, but not
on ESB2.

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, 14 insertions, 0 deletions

diff --git a/drivers/net/e1000e/lib.c b/drivers/net/e1000e/lib.c
index a86c17548c1e..56b59e4a6871 100644
--- a/drivers/net/e1000e/lib.c
+++ b/drivers/net/e1000e/lib.c
@@ -1609,6 +1609,11 @@ void e1000e_reset_adaptive(struct e1000_hw *hw)
 {
         struct e1000_mac_info *mac = &hw->mac;
 
+        if (!mac->adaptive_ifs) {
+                e_dbg("Not in Adaptive IFS mode!\n");
+                goto out;
+        }
+
         mac->current_ifs_val = 0;
         mac->ifs_min_val = IFS_MIN;
         mac->ifs_max_val = IFS_MAX;
@@ -1617,6 +1622,8 @@ void e1000e_reset_adaptive(struct e1000_hw *hw)
 
         mac->in_ifs_mode = false;
         ew32(AIT, 0);
+out:
+        return;
 }
 
 /**
@@ -1630,6 +1637,11 @@ void e1000e_update_adaptive(struct e1000_hw *hw)
 {
         struct e1000_mac_info *mac = &hw->mac;
 
+        if (!mac->adaptive_ifs) {
+                e_dbg("Not in Adaptive IFS mode!\n");
+                goto out;
+        }
+
         if ((mac->collision_delta * mac->ifs_ratio) > mac->tx_packet_delta) {
                 if (mac->tx_packet_delta > MIN_NUM_XMITS) {
                         mac->in_ifs_mode = true;
@@ -1650,6 +1662,8 @@ void e1000e_update_adaptive(struct e1000_hw *hw)
                         ew32(AIT, 0);
                 }
         }
+out:
+        return;
 }
 
 /**