[TG3]: Fix tg3_restart_ints()

tg3_restart_ints() is called to re-enable interrupts after tg3_poll()
has finished all the work. It calls tg3_cond_int() to force an interrupt
if the status block updated bit is set. The updated bit will be set if
there is a new status block update sometime during tg3_poll() and it can
be very often. The worst part is that even if all the work has been
processed, the updated bit remains set and an interrupt will be forced
unnecessarily.

The fix is to call tg3_has_work() instead to determine if new work is
posted before forcing an interrupt. The way to force an interrupt is
also changed to use "coalesce_now" instead of "SETINT". The former is
generally a safer way to force the interrupt.

Also deleted the first parameter to tg3_has_work() which is unused.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -426,9 +426,30 @@ static void tg3_enable_ints(struct tg3 *tp)
 	tg3_cond_int(tp);
 }
 
+static inline unsigned int tg3_has_work(struct tg3 *tp)
+{
+	struct tg3_hw_status *sblk = tp->hw_status;
+	unsigned int work_exists = 0;
+
+	/* check for phy events */
+	if (!(tp->tg3_flags &
+	      (TG3_FLAG_USE_LINKCHG_REG |
+	       TG3_FLAG_POLL_SERDES))) {
+		if (sblk->status & SD_STATUS_LINK_CHG)
+			work_exists = 1;
+	}
+	/* check for RX/TX work to do */
+	if (sblk->idx[0].tx_consumer != tp->tx_cons ||
+	    sblk->idx[0].rx_producer != tp->rx_rcb_ptr)
+		work_exists = 1;
+
+	return work_exists;
+}
+
 /* tg3_restart_ints
- *  similar to tg3_enable_ints, but it can return without flushing the
- *  PIO write which reenables interrupts
+ *  similar to tg3_enable_ints, but it accurately determines whether there
+ *  is new work pending and can return without flushing the PIO write
+ *  which reenables interrupts 
  */
 static void tg3_restart_ints(struct tg3 *tp)
 {
@@ -437,7 +458,9 @@ static void tg3_restart_ints(struct tg3 *tp)
 	tw32_mailbox(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW, 0x00000000);
 	mmiowb();
 
-	tg3_cond_int(tp);
+	if (tg3_has_work(tp))
+		tw32(HOSTCC_MODE, tp->coalesce_mode |
+		     (HOSTCC_MODE_ENABLE | HOSTCC_MODE_NOW));
 }
 
 static inline void tg3_netif_stop(struct tg3 *tp)
@@ -2891,26 +2914,6 @@ static int tg3_poll(struct net_device *netdev, int *budget)
 	return (done ? 0 : 1);
 }
 
-static inline unsigned int tg3_has_work(struct net_device *dev, struct tg3 *tp)
-{
-	struct tg3_hw_status *sblk = tp->hw_status;
-	unsigned int work_exists = 0;
-
-	/* check for phy events */
-	if (!(tp->tg3_flags &
-	      (TG3_FLAG_USE_LINKCHG_REG |
-	       TG3_FLAG_POLL_SERDES))) {
-		if (sblk->status & SD_STATUS_LINK_CHG)
-			work_exists = 1;
-	}
-	/* check for RX/TX work to do */
-	if (sblk->idx[0].tx_consumer != tp->tx_cons ||
-	    sblk->idx[0].rx_producer != tp->rx_rcb_ptr)
-		work_exists = 1;
-
-	return work_exists;
-}
-
 /* MSI ISR - No need to check for interrupt sharing and no need to
  * flush status block and interrupt mailbox. PCI ordering rules
  * guarantee that MSI will arrive after the status block.
@@ -2934,7 +2937,7 @@ static irqreturn_t tg3_msi(int irq, void *dev_id, struct pt_regs *regs)
 	tw32_mailbox(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW, 0x00000001);
 	sblk->status &= ~SD_STATUS_UPDATED;
 
-	if (likely(tg3_has_work(dev, tp)))
+	if (likely(tg3_has_work(tp)))
 		netif_rx_schedule(dev);		/* schedule NAPI poll */
 	else {
 		/* no work, re-enable interrupts
@@ -2981,7 +2984,7 @@ static irqreturn_t tg3_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 		tr32(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW);
 		sblk->status &= ~SD_STATUS_UPDATED;
 
-		if (likely(tg3_has_work(dev, tp)))
+		if (likely(tg3_has_work(tp)))
 			netif_rx_schedule(dev);		/* schedule NAPI poll */
 		else {
 			/* no work, shared interrupt perhaps?  re-enable