net: calxedaxgmac: enable interrupts after napi_enable

Fix a race condition where the interrupt handler may have called
napi_schedule before napi_enable is called. This would disable interrupts
and never actually schedule napi to run.
Reported-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/calxeda/xgmac.c

@@ -959,9 +959,7 @@ static int xgmac_hw_init(struct net_device *dev)
 		DMA_BUS_MODE_FB | DMA_BUS_MODE_ATDS | DMA_BUS_MODE_AAL;
 	writel(value, ioaddr + XGMAC_DMA_BUS_MODE);
 
-	/* Enable interrupts */
-	writel(DMA_INTR_DEFAULT_MASK, ioaddr + XGMAC_DMA_STATUS);
-	writel(DMA_INTR_DEFAULT_MASK, ioaddr + XGMAC_DMA_INTR_ENA);
+	writel(0, ioaddr + XGMAC_DMA_INTR_ENA);
 
 	/* Mask power mgt interrupt */
 	writel(XGMAC_INT_STAT_PMTIM, ioaddr + XGMAC_INT_STAT);
@@ -1029,6 +1027,10 @@ static int xgmac_open(struct net_device *dev)
 	napi_enable(&priv->napi);
 	netif_start_queue(dev);
 
+	/* Enable interrupts */
+	writel(DMA_INTR_DEFAULT_MASK, ioaddr + XGMAC_DMA_STATUS);
+	writel(DMA_INTR_DEFAULT_MASK, ioaddr + XGMAC_DMA_INTR_ENA);
+
 	return 0;
 }