e1000: Fix MSI only interrupt handler routine

Unfortunately the read-free MSI interrupt handler needs to flush write
the icr register and thus we can't be read-free. Our MSI irq routine
thus becomes a lot more simpler since we don't need to track link state
anymore.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>

2 files changed, 19 insertions, 42 deletions

diff --git a/drivers/net/e1000/e1000.h b/drivers/net/e1000/e1000.h
index f091042b146e..8e7acb08d9a3 100644
--- a/drivers/net/e1000/e1000.h
+++ b/drivers/net/e1000/e1000.h
@@ -257,7 +257,6 @@ struct e1000_adapter {
         spinlock_t tx_queue_lock;
 #endif
         atomic_t irq_sem;
-        unsigned int detect_link;
         unsigned int total_tx_bytes;
         unsigned int total_tx_packets;
         unsigned int total_rx_bytes;
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index c6259c7127f6..d408949d61dd 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -3765,8 +3765,8 @@ e1000_update_stats(struct e1000_adapter *adapter)
  * @data: pointer to a network interface device structure
  **/
 
-static
-irqreturn_t e1000_intr_msi(int irq, void *data)
+static irqreturn_t
+e1000_intr_msi(int irq, void *data)
 {
         struct net_device *netdev = data;
         struct e1000_adapter *adapter = netdev_priv(netdev);
@@ -3774,49 +3774,27 @@ irqreturn_t e1000_intr_msi(int irq, void *data)
 #ifndef CONFIG_E1000_NAPI
         int i;
 #endif
+        uint32_t icr = E1000_READ_REG(hw, ICR);
 
-        /* this code avoids the read of ICR but has to get 1000 interrupts
-         * at every link change event before it will notice the change */
-        if (++adapter->detect_link >= 1000) {
-                uint32_t icr = E1000_READ_REG(hw, ICR);
 #ifdef CONFIG_E1000_NAPI
-                /* read ICR disables interrupts using IAM, so keep up with our
-                 * enable/disable accounting */
-                atomic_inc(&adapter->irq_sem);
+        /* read ICR disables interrupts using IAM, so keep up with our
+         * enable/disable accounting */
+        atomic_inc(&adapter->irq_sem);
 #endif
-                adapter->detect_link = 0;
-                if ((icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) &&
-                    (icr & E1000_ICR_INT_ASSERTED)) {
-                        hw->get_link_status = 1;
-                        /* 80003ES2LAN workaround--
-                        * For packet buffer work-around on link down event;
-                        * disable receives here in the ISR and
-                        * reset adapter in watchdog
-                        */
-                        if (netif_carrier_ok(netdev) &&
-                            (adapter->hw.mac_type == e1000_80003es2lan)) {
-                                /* disable receives */
-                                uint32_t rctl = E1000_READ_REG(hw, RCTL);
-                                E1000_WRITE_REG(hw, RCTL, rctl & ~E1000_RCTL_EN);
-                        }
-                        /* guard against interrupt when we're going down */
-                        if (!test_bit(__E1000_DOWN, &adapter->flags))
-                                mod_timer(&adapter->watchdog_timer,
-                                          jiffies + 1);
+        if (icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) {
+                hw->get_link_status = 1;
+                /* 80003ES2LAN workaround-- For packet buffer work-around on
+                 * link down event; disable receives here in the ISR and reset
+                 * adapter in watchdog */
+                if (netif_carrier_ok(netdev) &&
+                    (adapter->hw.mac_type == e1000_80003es2lan)) {
+                        /* disable receives */
+                        uint32_t rctl = E1000_READ_REG(hw, RCTL);
+                        E1000_WRITE_REG(hw, RCTL, rctl & ~E1000_RCTL_EN);
                 }
-        } else {
-                E1000_WRITE_REG(hw, ICR, (0xffffffff & ~(E1000_ICR_RXSEQ |
-                                                         E1000_ICR_LSC)));
-                /* bummer we have to flush here, but things break otherwise as
-                 * some event appears to be lost or delayed and throughput
-                 * drops.  In almost all tests this flush is un-necessary */
-                E1000_WRITE_FLUSH(hw);
-#ifdef CONFIG_E1000_NAPI
-                /* Interrupt Auto-Mask (IAM)...upon writing ICR, interrupts are
-                 * masked.  No need for the IMC write, but it does mean we
-                 * should account for it ASAP. */
-                atomic_inc(&adapter->irq_sem);
-#endif
+                /* guard against interrupt when we're going down */
+                if (!test_bit(__E1000_DOWN, &adapter->flags))
+                        mod_timer(&adapter->watchdog_timer, jiffies + 1);
         }
 
 #ifdef CONFIG_E1000_NAPI