[TG3]: Set minimal hw interrupt mitigation.

Even though we do software interrupt mitigation
via NAPI, it still helps to have some minimal
hw assisted mitigation.

This helps, particularly, on systems where register
I/O overhead is much greater than the CPU horsepower.

For example, it helps on NUMA systems.  In such cases
the PIO overhead to disable interrupts for NAPI accounts
for the majority of the packet processing cost.  The
CPU is fast enough such that only a single packet is
processed by each NAPI poll call.

Thanks to Michael Chan for reviewing this patch.

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -2507,7 +2507,7 @@ static int tg3_setup_phy(struct tg3 *tp, int force_reset)
 	if (!(tp->tg3_flags2 & TG3_FLG2_5705_PLUS)) {
 		if (netif_carrier_ok(tp->dev)) {
 			tw32(HOSTCC_STAT_COAL_TICKS,
-			     DEFAULT_STAT_COAL_TICKS);
+			     tp->coal.stats_block_coalesce_usecs);
 		} else {
 			tw32(HOSTCC_STAT_COAL_TICKS, 0);
 		}
@@ -5094,6 +5094,27 @@ static void tg3_set_bdinfo(struct tg3 *tp, u32 bdinfo_addr,
 }
 
 static void __tg3_set_rx_mode(struct net_device *);
+static void tg3_set_coalesce(struct tg3 *tp, struct ethtool_coalesce *ec)
+{
+	tw32(HOSTCC_RXCOL_TICKS, ec->rx_coalesce_usecs);
+	tw32(HOSTCC_TXCOL_TICKS, ec->tx_coalesce_usecs);
+	tw32(HOSTCC_RXMAX_FRAMES, ec->rx_max_coalesced_frames);
+	tw32(HOSTCC_TXMAX_FRAMES, ec->tx_max_coalesced_frames);
+	if (!(tp->tg3_flags2 & TG3_FLG2_5705_PLUS)) {
+		tw32(HOSTCC_RXCOAL_TICK_INT, ec->rx_coalesce_usecs_irq);
+		tw32(HOSTCC_TXCOAL_TICK_INT, ec->tx_coalesce_usecs_irq);
+	}
+	tw32(HOSTCC_RXCOAL_MAXF_INT, ec->rx_max_coalesced_frames_irq);
+	tw32(HOSTCC_TXCOAL_MAXF_INT, ec->tx_max_coalesced_frames_irq);
+	if (!(tp->tg3_flags2 & TG3_FLG2_5705_PLUS)) {
+		u32 val = ec->stats_block_coalesce_usecs;
+
+		if (!netif_carrier_ok(tp->dev))
+			val = 0;
+
+		tw32(HOSTCC_STAT_COAL_TICKS, val);
+	}
+}
 
 /* tp->lock is held. */
 static int tg3_reset_hw(struct tg3 *tp)
@@ -5416,16 +5437,7 @@ static int tg3_reset_hw(struct tg3 *tp)
 		udelay(10);
 	}
 
-	tw32(HOSTCC_RXCOL_TICKS, 0);
-	tw32(HOSTCC_TXCOL_TICKS, LOW_TXCOL_TICKS);
-	tw32(HOSTCC_RXMAX_FRAMES, 1);
-	tw32(HOSTCC_TXMAX_FRAMES, LOW_RXMAX_FRAMES);
-	if (!(tp->tg3_flags2 & TG3_FLG2_5705_PLUS)) {
-		tw32(HOSTCC_RXCOAL_TICK_INT, 0);
-		tw32(HOSTCC_TXCOAL_TICK_INT, 0);
-	}
-	tw32(HOSTCC_RXCOAL_MAXF_INT, 1);
-	tw32(HOSTCC_TXCOAL_MAXF_INT, 0);
+	tg3_set_coalesce(tp, &tp->coal);
 
 	/* set status block DMA address */
 	tw32(HOSTCC_STATUS_BLK_HOST_ADDR + TG3_64BIT_REG_HIGH,
@@ -5438,8 +5450,6 @@ static int tg3_reset_hw(struct tg3 *tp)
 		 * the tg3_periodic_fetch_stats call there, and
 		 * tg3_get_stats to see how this works for 5705/5750 chips.
 		 */
-		tw32(HOSTCC_STAT_COAL_TICKS,
-		     DEFAULT_STAT_COAL_TICKS);
 		tw32(HOSTCC_STATS_BLK_HOST_ADDR + TG3_64BIT_REG_HIGH,
 		     ((u64) tp->stats_mapping >> 32));
 		tw32(HOSTCC_STATS_BLK_HOST_ADDR + TG3_64BIT_REG_LOW,
@@ -7284,6 +7294,14 @@ static void tg3_vlan_rx_kill_vid(struct net_device *dev, unsigned short vid)
 }
 #endif
 
+static int tg3_get_coalesce(struct net_device *dev, struct ethtool_coalesce *ec)
+{
+	struct tg3 *tp = netdev_priv(dev);
+
+	memcpy(ec, &tp->coal, sizeof(*ec));
+	return 0;
+}
+
 static struct ethtool_ops tg3_ethtool_ops = {
 	.get_settings		= tg3_get_settings,
 	.set_settings		= tg3_set_settings,
@@ -7316,6 +7334,7 @@ static struct ethtool_ops tg3_ethtool_ops = {
 	.get_strings		= tg3_get_strings,
 	.get_stats_count	= tg3_get_stats_count,
 	.get_ethtool_stats	= tg3_get_ethtool_stats,
+	.get_coalesce		= tg3_get_coalesce,
 };
 
 static void __devinit tg3_get_eeprom_size(struct tg3 *tp)
@@ -9096,6 +9115,31 @@ static struct pci_dev * __devinit tg3_find_5704_peer(struct tg3 *tp)
 	return peer;
 }
 
+static void __devinit tg3_init_coal(struct tg3 *tp)
+{
+	struct ethtool_coalesce *ec = &tp->coal;
+
+	memset(ec, 0, sizeof(*ec));
+	ec->cmd = ETHTOOL_GCOALESCE;
+	ec->rx_coalesce_usecs = LOW_RXCOL_TICKS;
+	ec->tx_coalesce_usecs = LOW_TXCOL_TICKS;
+	ec->rx_max_coalesced_frames = LOW_RXMAX_FRAMES;
+	ec->tx_max_coalesced_frames = LOW_TXMAX_FRAMES;
+	ec->rx_coalesce_usecs_irq = DEFAULT_RXCOAL_TICK_INT;
+	ec->tx_coalesce_usecs_irq = DEFAULT_TXCOAL_TICK_INT;
+	ec->rx_max_coalesced_frames_irq = DEFAULT_RXCOAL_MAXF_INT;
+	ec->tx_max_coalesced_frames_irq = DEFAULT_TXCOAL_MAXF_INT;
+	ec->stats_block_coalesce_usecs = DEFAULT_STAT_COAL_TICKS;
+
+	if (tp->coalesce_mode & (HOSTCC_MODE_CLRTICK_RXBD |
+				 HOSTCC_MODE_CLRTICK_TXBD)) {
+		ec->rx_coalesce_usecs = LOW_RXCOL_TICKS_CLRTCKS;
+		ec->rx_coalesce_usecs_irq = DEFAULT_RXCOAL_TICK_INT_CLRTCKS;
+		ec->tx_coalesce_usecs = LOW_TXCOL_TICKS_CLRTCKS;
+		ec->tx_coalesce_usecs_irq = DEFAULT_TXCOAL_TICK_INT_CLRTCKS;
+	}
+}
+
 static int __devinit tg3_init_one(struct pci_dev *pdev,
 				  const struct pci_device_id *ent)
 {
@@ -9341,6 +9385,8 @@ static int __devinit tg3_init_one(struct pci_dev *pdev,
 	/* flow control autonegotiation is default behavior */
 	tp->tg3_flags |= TG3_FLAG_PAUSE_AUTONEG;
 
+	tg3_init_coal(tp);
+
 	err = register_netdev(dev);
 	if (err) {
 		printk(KERN_ERR PFX "Cannot register net device, "

drivers/net/tg3.h

@@ -876,10 +876,12 @@
 #define  HOSTCC_STATUS_ERROR_ATTN	 0x00000004
 #define HOSTCC_RXCOL_TICKS		0x00003c08
 #define  LOW_RXCOL_TICKS		 0x00000032
+#define  LOW_RXCOL_TICKS_CLRTCKS	 0x00000014
 #define  DEFAULT_RXCOL_TICKS		 0x00000048
 #define  HIGH_RXCOL_TICKS		 0x00000096
 #define HOSTCC_TXCOL_TICKS		0x00003c0c
 #define  LOW_TXCOL_TICKS		 0x00000096
+#define  LOW_TXCOL_TICKS_CLRTCKS	 0x00000048
 #define  DEFAULT_TXCOL_TICKS		 0x0000012c
 #define  HIGH_TXCOL_TICKS		 0x00000145
 #define HOSTCC_RXMAX_FRAMES		0x00003c10
@@ -892,8 +894,10 @@
 #define  HIGH_TXMAX_FRAMES		 0x00000052
 #define HOSTCC_RXCOAL_TICK_INT		0x00003c18
 #define  DEFAULT_RXCOAL_TICK_INT	 0x00000019
+#define  DEFAULT_RXCOAL_TICK_INT_CLRTCKS 0x00000014
 #define HOSTCC_TXCOAL_TICK_INT		0x00003c1c
 #define  DEFAULT_TXCOAL_TICK_INT	 0x00000019
+#define  DEFAULT_TXCOAL_TICK_INT_CLRTCKS 0x00000014
 #define HOSTCC_RXCOAL_MAXF_INT		0x00003c20
 #define  DEFAULT_RXCOAL_MAXF_INT	 0x00000005
 #define HOSTCC_TXCOAL_MAXF_INT		0x00003c24
@@ -2227,7 +2231,7 @@ struct tg3 {
 
 #define SST_25VF0X0_PAGE_SIZE		4098
 
-
+	struct ethtool_coalesce		coal;
 };
 
 #endif /* !(_T3_H) */