[PATCH] sky2: changing mtu doesn't have to reset link

Changing the MTU of the network device doesn't mean the whole link
has to be brought down and back up again.  Just stopping the receive
engine is good enough.

Signed-off-by: Stephen Hemminger <shmminger @osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/net/sky2.c

@@ -468,9 +468,9 @@ static void sky2_mac_init(struct sky2_hw *hw, unsigned port)
 
 	/* serial mode register */
 	reg = DATA_BLIND_VAL(DATA_BLIND_DEF) |
-	    GM_SMOD_VLAN_ENA | IPG_DATA_VAL(IPG_DATA_DEF);
+		GM_SMOD_VLAN_ENA | IPG_DATA_VAL(IPG_DATA_DEF);
 
-	if (hw->dev[port]->mtu > 1500)
+	if (hw->dev[port]->mtu > ETH_DATA_LEN)
 		reg |= GM_SMOD_JUMBO_ENA;
 
 	gma_write16(hw, port, GM_SERIAL_MODE, reg);
@@ -515,8 +515,6 @@ static void sky2_ramset(struct sky2_hw *hw, u16 q, u32 start, size_t len)
 	len /= 8;
 	end = start + len - 1;
 
-	pr_debug("sky2_ramset start=%d end=%d\n", start, end);
-
 	sky2_write8(hw, RB_ADDR(q, RB_CTRL), RB_RST_CLR);
 	sky2_write32(hw, RB_ADDR(q, RB_START), start);
 	sky2_write32(hw, RB_ADDR(q, RB_END), end);
@@ -528,7 +526,6 @@ static void sky2_ramset(struct sky2_hw *hw, u16 q, u32 start, size_t len)
 
 		rxlo = len/2;
 		rxup = rxlo + len/4;
-		pr_debug(" utpp=%d ltpp=%d\n", rxup, rxlo);
 
 		/* Set thresholds on receive queue's */
 		sky2_write32(hw, RB_ADDR(q, RB_RX_UTPP), rxup);
@@ -662,16 +659,44 @@ static void rx_set_checksum(struct sky2_port *sky2)
 	le->ctrl = 0;
 	le->opcode = OP_TCPSTART | HW_OWNER;
 
-	sky2_write16(sky2->hw, Y2_QADDR(rxqaddr[sky2->port],
-					PREF_UNIT_PUT_IDX), sky2->rx_put);
-	sky2_read16(sky2->hw, Y2_QADDR(rxqaddr[sky2->port], PREF_UNIT_PUT_IDX));
-	mdelay(1);
 	sky2_write32(sky2->hw,
 		     Q_ADDR(rxqaddr[sky2->port], Q_CSR),
 		     sky2->rx_csum ? BMU_ENA_RX_CHKSUM : BMU_DIS_RX_CHKSUM);
 
 }
 
+/*
+ * The RX Stop command will not work for Yukon-2 if the BMU does not
+ * reach the end of packet and since we can't make sure that we have
+ * incoming data, we must reset the BMU while it is not doing a DMA
+ * transfer. Since it is possible that the RX path is still active,
+ * the RX RAM buffer will be stopped first, so any possible incoming
+ * data will not trigger a DMA. After the RAM buffer is stopped, the
+ * BMU is polled until any DMA in progress is ended and only then it
+ * will be reset.
+ */
+static void sky2_rx_stop(struct sky2_port *sky2)
+{
+	struct sky2_hw *hw = sky2->hw;
+	unsigned rxq = rxqaddr[sky2->port];
+	int i;
+
+	/* disable the RAM Buffer receive queue */
+	sky2_write8(hw, RB_ADDR(rxq, RB_CTRL), RB_DIS_OP_MD);
+
+	for (i = 0; i < 0xffff; i++)
+		if (sky2_read8(hw, RB_ADDR(rxq, Q_RSL))
+		    == sky2_read8(hw, RB_ADDR(rxq, Q_RL)))
+			goto stopped;
+
+	printk(KERN_WARNING PFX "%s: receiver stop failed\n",
+	       sky2->netdev->name);
+stopped:
+	sky2_write32(hw, Q_ADDR(rxq, Q_CSR), BMU_RST_SET | BMU_FIFO_RST);
+
+	/* reset the Rx prefetch unit */
+	sky2_write32(hw, Y2_QADDR(rxq, PREF_UNIT_CTRL), PREF_UNIT_RST_SET);
+}
 
 /* Cleanout receive buffer area, assumes receiver hardware stopped */
 static void sky2_rx_clean(struct sky2_port *sky2)
@@ -693,7 +718,7 @@ static void sky2_rx_clean(struct sky2_port *sky2)
 }
 
 #define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))
-static inline unsigned sky2_rx_size(const struct sky2_port *sky2)
+static inline unsigned rx_size(const struct sky2_port *sky2)
 {
 	return roundup(sky2->netdev->mtu + ETH_HLEN + 4, 8);
 }
@@ -709,12 +734,18 @@ static inline unsigned sky2_rx_size(const struct sky2_port *sky2)
  * is not aligned.  This means we can't use skb_reserve to align
  * the IP header.
  */
-static int sky2_rx_fill(struct sky2_port *sky2)
+static int sky2_rx_start(struct sky2_port *sky2)
 {
-	unsigned i;
-	unsigned size = sky2_rx_size(sky2);
+	struct sky2_hw *hw = sky2->hw;
+	unsigned size = rx_size(sky2);
+	unsigned rxq = rxqaddr[sky2->port];
+	int i;
+
+	sky2->rx_put = sky2->rx_next = 0;
+	sky2_qset(hw, rxq, is_pciex(hw) ? 0x80 : 0x600);
+	sky2_prefetch_init(hw, rxq, sky2->rx_le_map, RX_LE_SIZE - 1);
 
-	pr_debug("rx_fill size=%d\n", size);
+	rx_set_checksum(sky2);
 	for (i = 0; i < sky2->rx_pending; i++) {
 		struct ring_info *re = sky2->rx_ring + i;
 
@@ -722,12 +753,15 @@ static int sky2_rx_fill(struct sky2_port *sky2)
 		if (!re->skb)
 			goto nomem;
 
-		re->mapaddr = pci_map_single(sky2->hw->pdev, re->skb->data,
+		re->mapaddr = pci_map_single(hw->pdev, re->skb->data,
 					     size, PCI_DMA_FROMDEVICE);
 		re->maplen = size;
 		sky2_rx_add(sky2, re);
 	}
 
+	/* Tell chip about available buffers */
+	sky2_write16(hw, Y2_QADDR(rxq, PREF_UNIT_PUT_IDX), sky2->rx_put);
+	sky2->rx_last_put = sky2_read16(hw, Y2_QADDR(rxq, PREF_UNIT_PUT_IDX));
 	return 0;
 nomem:
 	sky2_rx_clean(sky2);
@@ -792,28 +826,14 @@ static int sky2_up(struct net_device *dev)
 	sky2_write8(hw, RB_ADDR(port == 0 ? Q_XS1 : Q_XS2, RB_CTRL),
 		    RB_RST_SET);
 
-	sky2_qset(hw, rxqaddr[port], is_pciex(hw) ? 0x80 : 0x600);
 	sky2_qset(hw, txqaddr[port], 0x600);
+	sky2_prefetch_init(hw, txqaddr[port], sky2->tx_le_map,
+			   TX_RING_SIZE - 1);
 
-	sky2->rx_put = sky2->rx_next = 0;
-	sky2_prefetch_init(hw, rxqaddr[port], sky2->rx_le_map, RX_LE_SIZE - 1);
-
-	rx_set_checksum(sky2);
-
-	err = sky2_rx_fill(sky2);
+	err = sky2_rx_start(sky2);
 	if (err)
 		goto err_out;
 
-	/* Give buffers to receiver */
-	sky2_write16(sky2->hw, Y2_QADDR(rxqaddr[port], PREF_UNIT_PUT_IDX),
-		     sky2->rx_put);
-	sky2->rx_last_put = sky2_read16(sky2->hw,
-					Y2_QADDR(rxqaddr[port],
-						 PREF_UNIT_PUT_IDX));
-
-	sky2_prefetch_init(hw, txqaddr[port], sky2->tx_le_map,
-			   TX_RING_SIZE - 1);
-
 	/* Enable interrupts from phy/mac for port */
 	hw->intr_mask |= (port == 0) ? Y2_IS_PORT_1 : Y2_IS_PORT_2;
 	sky2_write32(hw, B0_IMSK, hw->intr_mask);
@@ -1076,7 +1096,6 @@ static int sky2_down(struct net_device *dev)
 	struct sky2_hw *hw = sky2->hw;
 	unsigned port = sky2->port;
 	u16 ctrl;
-	int i;
 
 	if (netif_msg_ifdown(sky2))
 		printk(KERN_INFO PFX "%s: disabling interface\n", dev->name);
@@ -1121,30 +1140,7 @@ static int sky2_down(struct net_device *dev)
 
 	sky2_write32(hw, RB_ADDR(txqaddr[port], RB_CTRL), RB_RST_SET);
 
-	/*
-	 * The RX Stop command will not work for Yukon-2 if the BMU does not
-	 * reach the end of packet and since we can't make sure that we have
-	 * incoming data, we must reset the BMU while it is not doing a DMA
-	 * transfer. Since it is possible that the RX path is still active,
-	 * the RX RAM buffer will be stopped first, so any possible incoming
-	 * data will not trigger a DMA. After the RAM buffer is stopped, the
-	 * BMU is polled until any DMA in progress is ended and only then it
-	 * will be reset.
-	 */
-
-	/* disable the RAM Buffer receive queue */
-	sky2_write8(hw, RB_ADDR(rxqaddr[port], RB_CTRL), RB_DIS_OP_MD);
-
-	for (i = 0; i < 0xffff; i++)
-		if (sky2_read8(hw, RB_ADDR(rxqaddr[port], Q_RSL))
-		    == sky2_read8(hw, RB_ADDR(rxqaddr[port], Q_RL)))
-			break;
-
-	sky2_write32(hw, Q_ADDR(rxqaddr[port], Q_CSR),
-		     BMU_RST_SET | BMU_FIFO_RST);
-	/* reset the Rx prefetch unit */
-	sky2_write32(hw, Y2_QADDR(rxqaddr[port], PREF_UNIT_CTRL),
-		     PREF_UNIT_RST_SET);
+	sky2_rx_stop(sky2);
 
 	sky2_write8(hw, SK_REG(port, RX_GMF_CTRL_T), GMF_RST_SET);
 	sky2_write8(hw, SK_REG(port, TX_GMF_CTRL_T), GMF_RST_SET);
@@ -1379,19 +1375,44 @@ static void sky2_tx_timeout(struct net_device *dev)
 
 static int sky2_change_mtu(struct net_device *dev, int new_mtu)
 {
-	int err = 0;
+	struct sky2_port *sky2 = netdev_priv(dev);
+	struct sky2_hw *hw = sky2->hw;
+	int err;
+	u16 ctl, mode;
 
 	if (new_mtu < ETH_ZLEN || new_mtu > ETH_JUMBO_MTU)
 		return -EINVAL;
 
-	if (netif_running(dev))
-		sky2_down(dev);
+	if (!netif_running(dev)) {
+		dev->mtu = new_mtu;
+		return 0;
+	}
+
+	local_irq_disable();
+	sky2_write32(hw, B0_IMSK, 0);
+
+	ctl = gma_read16(hw, sky2->port, GM_GP_CTRL);
+	gma_write16(hw, sky2->port, GM_GP_CTRL, ctl & ~GM_GPCR_RX_ENA);
+	sky2_rx_stop(sky2);
+	sky2_rx_clean(sky2);
 
 	dev->mtu = new_mtu;
+	mode = DATA_BLIND_VAL(DATA_BLIND_DEF) |
+		GM_SMOD_VLAN_ENA | IPG_DATA_VAL(IPG_DATA_DEF);
 
-	if (netif_running(dev))
-		err = sky2_up(dev);
+	if (dev->mtu > ETH_DATA_LEN)
+		mode |= GM_SMOD_JUMBO_ENA;
+
+	gma_write16(hw, sky2->port, GM_SERIAL_MODE, mode);
+
+	sky2_write8(hw, RB_ADDR(rxqaddr[sky2->port], RB_CTRL), RB_ENA_OP_MD);
+
+	err = sky2_rx_start(sky2);
+	gma_write16(hw, sky2->port, GM_GP_CTRL, ctl);
 
+	sky2_write32(hw, B0_IMSK, hw->intr_mask);
+	sky2_read32(hw, B0_IMSK);
+	local_irq_enable();
 	return err;
 }
 
@@ -1407,7 +1428,7 @@ static struct sk_buff *sky2_receive(struct sky2_hw *hw, unsigned port,
 	struct sky2_port *sky2 = netdev_priv(dev);
 	struct ring_info *re = sky2->rx_ring + sky2->rx_next;
 	struct sk_buff *skb = NULL;
-	const unsigned int bufsize = sky2_rx_size(sky2);
+	const unsigned int bufsize = rx_size(sky2);
 
 	if (unlikely(netif_msg_rx_status(sky2)))
 		printk(KERN_DEBUG PFX "%s: rx slot %u status 0x%x len %d\n",