[net-next-2.6 PATCH 1/4] e1000e: avoid polling h/w registers during link negotiation

[Jeff Kirsher <jeffrey.t.kirsher@intel.com>]

From: Bruce Allan <bruce.w.allan@intel.com>

Avoid touching hardware registers when possible, otherwise link negotiation
can get messed up when user-level scripts are rapidly polling the driver to
see if/when link is up.  Use the saved link state information instead when
possible.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---

 drivers/net/e1000e/e1000.h   |    1 -
 drivers/net/e1000e/ethtool.c |   54 ++++++++++++++++++++++--------------------
 drivers/net/e1000e/netdev.c  |    2 +-
 3 files changed, 29 insertions(+), 28 deletions(-)

diff --git a/drivers/net/e1000e/e1000.h b/drivers/net/e1000e/e1000.h
index 328b7f4..9ee133f 100644
--- a/drivers/net/e1000e/e1000.h
+++ b/drivers/net/e1000e/e1000.h
@@ -461,7 +461,6 @@ extern int e1000e_setup_tx_resources(struct e1000_adapter *adapter);
 extern void e1000e_free_rx_resources(struct e1000_adapter *adapter);
 extern void e1000e_free_tx_resources(struct e1000_adapter *adapter);
 extern void e1000e_update_stats(struct e1000_adapter *adapter);
-extern bool e1000e_has_link(struct e1000_adapter *adapter);
 extern void e1000e_set_interrupt_capability(struct e1000_adapter *adapter);
 extern void e1000e_reset_interrupt_capability(struct e1000_adapter *adapter);
 extern void e1000e_disable_aspm(struct pci_dev *pdev, u16 state);
diff --git a/drivers/net/e1000e/ethtool.c b/drivers/net/e1000e/ethtool.c
index db86850..77c5829 100644
--- a/drivers/net/e1000e/ethtool.c
+++ b/drivers/net/e1000e/ethtool.c
@@ -118,7 +118,6 @@ static int e1000_get_settings(struct net_device *netdev,
 {
 	struct e1000_adapter *adapter = netdev_priv(netdev);
 	struct e1000_hw *hw = &adapter->hw;
-	u32 status;
 
 	if (hw->phy.media_type == e1000_media_type_copper) {
 
@@ -156,22 +155,29 @@ static int e1000_get_settings(struct net_device *netdev,
 		ecmd->transceiver = XCVR_EXTERNAL;
 	}
 
-	status = er32(STATUS);
-	if (status & E1000_STATUS_LU) {
-		if (status & E1000_STATUS_SPEED_1000)
-			ecmd->speed = 1000;
-		else if (status & E1000_STATUS_SPEED_100)
-			ecmd->speed = 100;
-		else
-			ecmd->speed = 10;
+	ecmd->speed = -1;
+	ecmd->duplex = -1;
 
-		if (status & E1000_STATUS_FD)
-			ecmd->duplex = DUPLEX_FULL;
-		else
-			ecmd->duplex = DUPLEX_HALF;
+	if (netif_running(netdev)) {
+		if (netif_carrier_ok(netdev)) {
+			ecmd->speed = adapter->link_speed;
+			ecmd->duplex = adapter->link_duplex - 1;
+		}
 	} else {
-		ecmd->speed = -1;
-		ecmd->duplex = -1;
+		u32 status = er32(STATUS);
+		if (status & E1000_STATUS_LU) {
+			if (status & E1000_STATUS_SPEED_1000)
+				ecmd->speed = 1000;
+			else if (status & E1000_STATUS_SPEED_100)
+				ecmd->speed = 100;
+			else
+				ecmd->speed = 10;
+
+			if (status & E1000_STATUS_FD)
+				ecmd->duplex = DUPLEX_FULL;
+			else
+				ecmd->duplex = DUPLEX_HALF;
+		}
 	}
 
 	ecmd->autoneg = ((hw->phy.media_type == e1000_media_type_fiber) ||
@@ -179,7 +185,7 @@ static int e1000_get_settings(struct net_device *netdev,
 
 	/* MDI-X => 2; MDI =>1; Invalid =>0 */
 	if ((hw->phy.media_type == e1000_media_type_copper) &&
-	    !hw->mac.get_link_status)
+	    netif_carrier_ok(netdev))
 		ecmd->eth_tp_mdix = hw->phy.is_mdix ? ETH_TP_MDI_X :
 		                                      ETH_TP_MDI;
 	else
@@ -191,19 +197,15 @@ static int e1000_get_settings(struct net_device *netdev,
 static u32 e1000_get_link(struct net_device *netdev)
 {
 	struct e1000_adapter *adapter = netdev_priv(netdev);
-	struct e1000_mac_info *mac = &adapter->hw.mac;
+	struct e1000_hw *hw = &adapter->hw;
 
 	/*
-	 * If the link is not reported up to netdev, interrupts are disabled,
-	 * and so the physical link state may have changed since we last
-	 * looked. Set get_link_status to make sure that the true link
-	 * state is interrogated, rather than pulling a cached and possibly
-	 * stale link state from the driver.
+	 * Avoid touching hardware registers when possible, otherwise
+	 * link negotiation can get messed up when user-level scripts
+	 * are rapidly polling the driver to see if link is up.
 	 */
-	if (!netif_carrier_ok(netdev))
-		mac->get_link_status = 1;
-
-	return e1000e_has_link(adapter);
+	return netif_running(netdev) ? netif_carrier_ok(netdev) :
+	    !!(er32(STATUS) & E1000_STATUS_LU);
 }
 
 static int e1000_set_spd_dplx(struct e1000_adapter *adapter, u16 spddplx)
diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index 8faf224..2a71889 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -3964,7 +3964,7 @@ static void e1000_print_link_info(struct e1000_adapter *adapter)
 	       ((ctrl & E1000_CTRL_TFCE) ? "TX" : "None" )));
 }
 
-bool e1000e_has_link(struct e1000_adapter *adapter)
+static bool e1000e_has_link(struct e1000_adapter *adapter)
 {
 	struct e1000_hw *hw = &adapter->hw;
 	bool link_active = 0;