e1000e: do not modify tx_queue_len on link speed change

Previously the driver tweaked txqueuelen to avoid false Tx hang reports seen at half duplex.
This had the effect of overriding user set values on link change/reset. Testing shows that
adjusting only the timeout factor is sufficient to prevent Tx hang reports at half duplex.

This patch removes all instances of tx_queue_len in the driver.

Originally reported and patched by Franco Fichtner
CC: Franco Fichtner <franco@lastsummer.de>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/e1000e/e1000.h

@@ -279,7 +279,6 @@ struct e1000_adapter {
 
 	struct napi_struct napi;
 
-	unsigned long tx_queue_len;
 	unsigned int restart_queue;
 	u32 txd_cmd;
 

drivers/net/e1000e/netdev.c

@@ -2289,8 +2289,6 @@ static void e1000_configure_tx(struct e1000_adapter *adapter)
 	ew32(TCTL, tctl);
 
 	e1000e_config_collision_dist(hw);
-
-	adapter->tx_queue_len = adapter->netdev->tx_queue_len;
 }
 
 /**
@@ -2877,7 +2875,6 @@ void e1000e_down(struct e1000_adapter *adapter)
 	del_timer_sync(&adapter->watchdog_timer);
 	del_timer_sync(&adapter->phy_info_timer);
 
-	netdev->tx_queue_len = adapter->tx_queue_len;
 	netif_carrier_off(netdev);
 	adapter->link_speed = 0;
 	adapter->link_duplex = 0;
@@ -3588,21 +3585,15 @@ static void e1000_watchdog_task(struct work_struct *work)
 					       "link gets many collisions.\n");
 			}
 
-			/*
-			 * tweak tx_queue_len according to speed/duplex
-			 * and adjust the timeout factor
-			 */
-			netdev->tx_queue_len = adapter->tx_queue_len;
+			/* adjust timeout factor according to speed/duplex */
 			adapter->tx_timeout_factor = 1;
 			switch (adapter->link_speed) {
 			case SPEED_10:
 				txb2b = 0;
-				netdev->tx_queue_len = 10;
 				adapter->tx_timeout_factor = 16;
 				break;
 			case SPEED_100:
 				txb2b = 0;
-				netdev->tx_queue_len = 100;
 				adapter->tx_timeout_factor = 10;
 				break;
 			}