[PATCH] sky2: transmit recovery

This patch decodes state and revovers from any races in the transmit
timeout and NAPI logic. It should never trigger, but if it does then
do the right thing.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/sky2.c

@@ -1328,7 +1328,7 @@ static void sky2_tx_complete(struct sky2_port *sky2, u16 done)
 	}
 
 	sky2->tx_cons = put;
-	if (netif_queue_stopped(dev) && tx_avail(sky2) > MAX_SKB_TX_LE)
+	if (tx_avail(sky2) > MAX_SKB_TX_LE)
 		netif_wake_queue(dev);
 }
 
@@ -1651,17 +1651,40 @@ static void sky2_tx_timeout(struct net_device *dev)
 	struct sky2_port *sky2 = netdev_priv(dev);
 	struct sky2_hw *hw = sky2->hw;
 	unsigned txq = txqaddr[sky2->port];
+	u16 report, done;
 
 	if (netif_msg_timer(sky2))
 		printk(KERN_ERR PFX "%s: tx timeout\n", dev->name);
 
-	sky2_write32(hw, Q_ADDR(txq, Q_CSR), BMU_STOP);
-	sky2_write32(hw, Y2_QADDR(txq, PREF_UNIT_CTRL), PREF_UNIT_RST_SET);
+	report = sky2_read16(hw, sky2->port == 0 ? STAT_TXA1_RIDX : STAT_TXA2_RIDX);
+	done = sky2_read16(hw, Q_ADDR(txq, Q_DONE));
 
-	sky2_tx_clean(sky2);
+	printk(KERN_DEBUG PFX "%s: transmit ring %u .. %u report=%u done=%u\n",
+	       dev->name,
+	       sky2->tx_cons, sky2->tx_prod, report, done);
+
+	if (report != done) {
+		printk(KERN_INFO PFX "status burst pending (irq moderation?)\n");
+
+		sky2_write8(hw, STAT_TX_TIMER_CTRL, TIM_STOP);
+		sky2_write8(hw, STAT_TX_TIMER_CTRL, TIM_START);
+	} else if (report != sky2->tx_cons) {
+		printk(KERN_INFO PFX "status report lost?\n");
 
-	sky2_qset(hw, txq);
-	sky2_prefetch_init(hw, txq, sky2->tx_le_map, TX_RING_SIZE - 1);
+		spin_lock_bh(&sky2->tx_lock);
+		sky2_tx_complete(sky2, report);
+		spin_unlock_bh(&sky2->tx_lock);
+	} else {
+		printk(KERN_INFO PFX "hardware hung? flushing\n");
+
+		sky2_write32(hw, Q_ADDR(txq, Q_CSR), BMU_STOP);
+		sky2_write32(hw, Y2_QADDR(txq, PREF_UNIT_CTRL), PREF_UNIT_RST_SET);
+
+		sky2_tx_clean(sky2);
+
+		sky2_qset(hw, txq);
+		sky2_prefetch_init(hw, txq, sky2->tx_le_map, TX_RING_SIZE - 1);
+	}
 }
 
 
@@ -2097,6 +2120,8 @@ static irqreturn_t sky2_intr(int irq, void *dev_id, struct pt_regs *regs)
 	prefetch(&hw->st_le[hw->st_idx]);
 	if (likely(__netif_rx_schedule_prep(dev0)))
 		__netif_rx_schedule(dev0);
+	else
+		printk(KERN_DEBUG PFX "irq race detected\n");
 
 	return IRQ_HANDLED;
 }