[PATCH] spidernet: rework tx queue handling

With this patch TX queue descriptors are not chained per default any more.
The pointer to next descriptor is set only when next descriptor is prepaired
for transfer. Also the mechanism of checking wether Spider is ready has been
changed: it checks not for CARDOWNED flag in status of previous descriptor
but for a TXDMAENABLED flag in Spider's register.

Signed-off-by: Maxim Shchetynin <maxim@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 253 insertions, 325 deletions

diff --git a/drivers/net/spider_net.c b/drivers/net/spider_net.c
index 05b474f2c8b..647f62e9707 100644
--- a/drivers/net/spider_net.c
+++ b/drivers/net/spider_net.c
@@ -84,7 +84,7 @@ MODULE_DEVICE_TABLE(pci, spider_net_pci_tbl);
  *
  * returns the content of the specified SMMIO register.
  */
-static u32
+static inline u32
 spider_net_read_reg(struct spider_net_card *card, u32 reg)
 {
 	u32 value;
@@ -101,7 +101,7 @@ spider_net_read_reg(struct spider_net_card *card, u32 reg)
  * @reg: register to write to
  * @value: value to write into the specified SMMIO register
  */
-static void
+static inline void
 spider_net_write_reg(struct spider_net_card *card, u32 reg, u32 value)
 {
 	value = cpu_to_le32(value);
@@ -259,39 +259,10 @@ spider_net_get_mac_address(struct net_device *netdev)
  *
  * returns the status as in the dmac_cmd_status field of the descriptor
  */
-static enum spider_net_descr_status
+static inline int
 spider_net_get_descr_status(struct spider_net_descr *descr)
 {
-	u32 cmd_status;
-
-	cmd_status = descr->dmac_cmd_status;
-	cmd_status >>= SPIDER_NET_DESCR_IND_PROC_SHIFT;
-	/* no need to mask out any bits, as cmd_status is 32 bits wide only
-	 * (and unsigned) */
-	return cmd_status;
-}
-
-/**
- * spider_net_set_descr_status -- sets the status of a descriptor
- * @descr: descriptor to change
- * @status: status to set in the descriptor
- *
- * changes the status to the specified value. Doesn't change other bits
- * in the status
- */
-static void
-spider_net_set_descr_status(struct spider_net_descr *descr,
-			    enum spider_net_descr_status status)
-{
-	u32 cmd_status;
-	/* read the status */
-	cmd_status = descr->dmac_cmd_status;
-	/* clean the upper 4 bits */
-	cmd_status &= SPIDER_NET_DESCR_IND_PROC_MASKO;
-	/* add the status to it */
-	cmd_status |= ((u32)status)<<SPIDER_NET_DESCR_IND_PROC_SHIFT;
-	/* and write it back */
-	descr->dmac_cmd_status = cmd_status;
+	return descr->dmac_cmd_status & SPIDER_NET_DESCR_IND_PROC_MASK;
 }
 
 /**
@@ -328,24 +299,23 @@ spider_net_free_chain(struct spider_net_card *card,
 static int
 spider_net_init_chain(struct spider_net_card *card,
 		       struct spider_net_descr_chain *chain,
-		       struct spider_net_descr *start_descr, int no)
+		       struct spider_net_descr *start_descr,
+		       int direction, int no)
 {
 	int i;
 	struct spider_net_descr *descr;
 	dma_addr_t buf;
 
-	atomic_set(&card->rx_chain_refill,0);
-
 	descr = start_descr;
 	memset(descr, 0, sizeof(*descr) * no);
 
 	/* set up the hardware pointers in each descriptor */
 	for (i=0; i<no; i++, descr++) {
-		spider_net_set_descr_status(descr, SPIDER_NET_DESCR_NOT_IN_USE);
+		descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
 
 		buf = pci_map_single(card->pdev, descr,
 				     SPIDER_NET_DESCR_SIZE,
-				     PCI_DMA_BIDIRECTIONAL);
+				     direction);
 
 		if (buf == DMA_ERROR_CODE)
 			goto iommu_error;
@@ -360,10 +330,11 @@ spider_net_init_chain(struct spider_net_card *card,
 	start_descr->prev = descr-1;
 
 	descr = start_descr;
-	for (i=0; i < no; i++, descr++) {
-		descr->next_descr_addr = descr->next->bus_addr;
-	}
+	if (direction == PCI_DMA_FROMDEVICE)
+		for (i=0; i < no; i++, descr++)
+			descr->next_descr_addr = descr->next->bus_addr;
 
+	spin_lock_init(&chain->lock);
 	chain->head = start_descr;
 	chain->tail = start_descr;
 
@@ -375,7 +346,7 @@ iommu_error:
 		if (descr->bus_addr)
 			pci_unmap_single(card->pdev, descr->bus_addr,
 					 SPIDER_NET_DESCR_SIZE,
-					 PCI_DMA_BIDIRECTIONAL);
+					 direction);
 	return -ENOMEM;
 }
 
@@ -396,7 +367,7 @@ spider_net_free_rx_chain_contents(struct spider_net_card *card)
 			dev_kfree_skb(descr->skb);
 			pci_unmap_single(card->pdev, descr->buf_addr,
 					 SPIDER_NET_MAX_FRAME,
-					 PCI_DMA_BIDIRECTIONAL);
+					 PCI_DMA_FROMDEVICE);
 		}
 		descr = descr->next;
 	}
@@ -446,15 +417,16 @@ spider_net_prepare_rx_descr(struct spider_net_card *card,
 		skb_reserve(descr->skb, SPIDER_NET_RXBUF_ALIGN - offset);
 	/* io-mmu-map the skb */
 	buf = pci_map_single(card->pdev, descr->skb->data,
-			     SPIDER_NET_MAX_FRAME, PCI_DMA_BIDIRECTIONAL);
+			SPIDER_NET_MAX_FRAME, PCI_DMA_FROMDEVICE);
 	descr->buf_addr = buf;
 	if (buf == DMA_ERROR_CODE) {
 		dev_kfree_skb_any(descr->skb);
 		if (netif_msg_rx_err(card) && net_ratelimit())
 			pr_err("Could not iommu-map rx buffer\n");
-		spider_net_set_descr_status(descr, SPIDER_NET_DESCR_NOT_IN_USE);
+		descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
 	} else {
-		descr->dmac_cmd_status = SPIDER_NET_DMAC_RX_CARDOWNED;
+		descr->dmac_cmd_status = SPIDER_NET_DESCR_CARDOWNED |
+					 SPIDER_NET_DMAC_NOINTR_COMPLETE;
 	}
 
 	return error;
@@ -468,7 +440,7 @@ spider_net_prepare_rx_descr(struct spider_net_card *card,
  * chip by writing to the appropriate register. DMA is enabled in
  * spider_net_enable_rxdmac.
  */
-static void
+static inline void
 spider_net_enable_rxchtails(struct spider_net_card *card)
 {
 	/* assume chain is aligned correctly */
@@ -483,7 +455,7 @@ spider_net_enable_rxchtails(struct spider_net_card *card)
  * spider_net_enable_rxdmac enables the DMA controller by setting RX_DMA_EN
  * in the GDADMACCNTR register
  */
-static void
+static inline void
 spider_net_enable_rxdmac(struct spider_net_card *card)
 {
 	wmb();
@@ -500,23 +472,24 @@ spider_net_enable_rxdmac(struct spider_net_card *card)
 static void
 spider_net_refill_rx_chain(struct spider_net_card *card)
 {
-	struct spider_net_descr_chain *chain;
-
-	chain = &card->rx_chain;
+	struct spider_net_descr_chain *chain = &card->rx_chain;
+	unsigned long flags;
 
 	/* one context doing the refill (and a second context seeing that
 	 * and omitting it) is ok. If called by NAPI, we'll be called again
 	 * as spider_net_decode_one_descr is called several times. If some
 	 * interrupt calls us, the NAPI is about to clean up anyway. */
-	if (atomic_inc_return(&card->rx_chain_refill) == 1)
-		while (spider_net_get_descr_status(chain->head) ==
-		       SPIDER_NET_DESCR_NOT_IN_USE) {
-			if (spider_net_prepare_rx_descr(card, chain->head))
-				break;
-			chain->head = chain->head->next;
-		}
+	if (!spin_trylock_irqsave(&chain->lock, flags))
+		return;
+
+	while (spider_net_get_descr_status(chain->head) ==
+			SPIDER_NET_DESCR_NOT_IN_USE) {
+		if (spider_net_prepare_rx_descr(card, chain->head))
+			break;
+		chain->head = chain->head->next;
+	}
 
-	atomic_dec(&card->rx_chain_refill);
+	spin_unlock_irqrestore(&chain->lock, flags);
 }
 
 /**
@@ -554,111 +527,6 @@ error:
 }
 
 /**
- * spider_net_release_tx_descr - processes a used tx descriptor
- * @card: card structure
- * @descr: descriptor to release
- *
- * releases a used tx descriptor (unmapping, freeing of skb)
- */
-static void
-spider_net_release_tx_descr(struct spider_net_card *card,
-			    struct spider_net_descr *descr)
-{
-	struct sk_buff *skb;
-
-	/* unmap the skb */
-	skb = descr->skb;
-	pci_unmap_single(card->pdev, descr->buf_addr, skb->len,
-			 PCI_DMA_BIDIRECTIONAL);
-
-	dev_kfree_skb_any(skb);
-
-	/* set status to not used */
-	spider_net_set_descr_status(descr, SPIDER_NET_DESCR_NOT_IN_USE);
-}
-
-/**
- * spider_net_release_tx_chain - processes sent tx descriptors
- * @card: adapter structure
- * @brutal: if set, don't care about whether descriptor seems to be in use
- *
- * returns 0 if the tx ring is empty, otherwise 1.
- *
- * spider_net_release_tx_chain releases the tx descriptors that spider has
- * finished with (if non-brutal) or simply release tx descriptors (if brutal).
- * If some other context is calling this function, we return 1 so that we're
- * scheduled again (if we were scheduled) and will not loose initiative.
- */
-static int
-spider_net_release_tx_chain(struct spider_net_card *card, int brutal)
-{
-	struct spider_net_descr_chain *tx_chain = &card->tx_chain;
-	enum spider_net_descr_status status;
-
-	if (atomic_inc_return(&card->tx_chain_release) != 1) {
-		atomic_dec(&card->tx_chain_release);
-		return 1;
-	}
-
-	for (;;) {
-		status = spider_net_get_descr_status(tx_chain->tail);
-		switch (status) {
-		case SPIDER_NET_DESCR_CARDOWNED:
-			if (!brutal)
-				goto out;
-			/* fallthrough, if we release the descriptors
-			 * brutally (then we don't care about
-			 * SPIDER_NET_DESCR_CARDOWNED) */
-		case SPIDER_NET_DESCR_RESPONSE_ERROR:
-		case SPIDER_NET_DESCR_PROTECTION_ERROR:
-		case SPIDER_NET_DESCR_FORCE_END:
-			if (netif_msg_tx_err(card))
-				pr_err("%s: forcing end of tx descriptor "
-				       "with status x%02x\n",
-				       card->netdev->name, status);
-			card->netdev_stats.tx_dropped++;
-			break;
-
-		case SPIDER_NET_DESCR_COMPLETE:
-			card->netdev_stats.tx_packets++;
-			card->netdev_stats.tx_bytes +=
-				tx_chain->tail->skb->len;
-			break;
-
-		default: /* any other value (== SPIDER_NET_DESCR_NOT_IN_USE) */
-			goto out;
-		}
-		spider_net_release_tx_descr(card, tx_chain->tail);
-		tx_chain->tail = tx_chain->tail->next;
-	}
-out:
-	atomic_dec(&card->tx_chain_release);
-
-	netif_wake_queue(card->netdev);
-
-	if (status == SPIDER_NET_DESCR_CARDOWNED)
-		return 1;
-	return 0;
-}
-
-/**
- * spider_net_cleanup_tx_ring - cleans up the TX ring
- * @card: card structure
- *
- * spider_net_cleanup_tx_ring is called by the tx_timer (as we don't use
- * interrupts to cleanup our TX ring) and returns sent packets to the stack
- * by freeing them
- */
-static void
-spider_net_cleanup_tx_ring(struct spider_net_card *card)
-{
-	if ( (spider_net_release_tx_chain(card, 0)) &&
-	      (card->netdev->flags & IFF_UP) ) {
-		mod_timer(&card->tx_timer, jiffies + SPIDER_NET_TX_TIMER);
-	}
-}
-
-/**
  * spider_net_get_multicast_hash - generates hash for multicast filter table
  * @addr: multicast address
  *
@@ -761,97 +629,6 @@ spider_net_disable_rxdmac(struct spider_net_card *card)
 }
 
 /**
- * spider_net_stop - called upon ifconfig down
- * @netdev: interface device structure
- *
- * always returns 0
- */
-int
-spider_net_stop(struct net_device *netdev)
-{
-	struct spider_net_card *card = netdev_priv(netdev);
-
-	tasklet_kill(&card->rxram_full_tl);
-	netif_poll_disable(netdev);
-	netif_carrier_off(netdev);
-	netif_stop_queue(netdev);
-	del_timer_sync(&card->tx_timer);
-
-	/* disable/mask all interrupts */
-	spider_net_write_reg(card, SPIDER_NET_GHIINT0MSK, 0);
-	spider_net_write_reg(card, SPIDER_NET_GHIINT1MSK, 0);
-	spider_net_write_reg(card, SPIDER_NET_GHIINT2MSK, 0);
-
-	/* free_irq(netdev->irq, netdev);*/
-	free_irq(to_pci_dev(netdev->class_dev.dev)->irq, netdev);
-
-	spider_net_write_reg(card, SPIDER_NET_GDTDMACCNTR,
-			     SPIDER_NET_DMA_TX_FEND_VALUE);
-
-	/* turn off DMA, force end */
-	spider_net_disable_rxdmac(card);
-
-	/* release chains */
-	spider_net_release_tx_chain(card, 1);
-
-	spider_net_free_chain(card, &card->tx_chain);
-	spider_net_free_chain(card, &card->rx_chain);
-
-	return 0;
-}
-
-/**
- * spider_net_get_next_tx_descr - returns the next available tx descriptor
- * @card: device structure to get descriptor from
- *
- * returns the address of the next descriptor, or NULL if not available.
- */
-static struct spider_net_descr *
-spider_net_get_next_tx_descr(struct spider_net_card *card)
-{
-	/* check, if head points to not-in-use descr */
-	if ( spider_net_get_descr_status(card->tx_chain.head) ==
-	     SPIDER_NET_DESCR_NOT_IN_USE ) {
-		return card->tx_chain.head;
-	} else {
-		return NULL;
-	}
-}
-
-/**
- * spider_net_set_txdescr_cmdstat - sets the tx descriptor command field
- * @descr: descriptor structure to fill out
- * @skb: packet to consider
- *
- * fills out the command and status field of the descriptor structure,
- * depending on hardware checksum settings.
- */
-static void
-spider_net_set_txdescr_cmdstat(struct spider_net_descr *descr,
-			       struct sk_buff *skb)
-{
-	/* make sure the other fields in the descriptor are written */
-	wmb();
-
-	if (skb->ip_summed != CHECKSUM_HW) {
-		descr->dmac_cmd_status = SPIDER_NET_DMAC_CMDSTAT_NOCS;
-		return;
-	}
-
-	/* is packet ip?
-	 * if yes: tcp? udp? */
-	if (skb->protocol == htons(ETH_P_IP)) {
-		if (skb->nh.iph->protocol == IPPROTO_TCP)
-			descr->dmac_cmd_status = SPIDER_NET_DMAC_CMDSTAT_TCPCS;
-		else if (skb->nh.iph->protocol == IPPROTO_UDP)
-			descr->dmac_cmd_status = SPIDER_NET_DMAC_CMDSTAT_UDPCS;
-		else /* the stack should checksum non-tcp and non-udp
-			packets on his own: NETIF_F_IP_CSUM */
-			descr->dmac_cmd_status = SPIDER_NET_DMAC_CMDSTAT_NOCS;
-	}
-}
-
-/**
  * spider_net_prepare_tx_descr - fill tx descriptor with skb data
  * @card: card structure
  * @descr: descriptor structure to fill out
@@ -864,13 +641,12 @@ spider_net_set_txdescr_cmdstat(struct spider_net_descr *descr,
  */
 static int
 spider_net_prepare_tx_descr(struct spider_net_card *card,
-			    struct spider_net_descr *descr,
 			    struct sk_buff *skb)
 {
+	struct spider_net_descr *descr = card->tx_chain.head;
 	dma_addr_t buf;
 
-	buf = pci_map_single(card->pdev, skb->data,
-			     skb->len, PCI_DMA_BIDIRECTIONAL);
+	buf = pci_map_single(card->pdev, skb->data, skb->len, PCI_DMA_TODEVICE);
 	if (buf == DMA_ERROR_CODE) {
 		if (netif_msg_tx_err(card) && net_ratelimit())
 			pr_err("could not iommu-map packet (%p, %i). "
@@ -880,10 +656,101 @@ spider_net_prepare_tx_descr(struct spider_net_card *card,
 
 	descr->buf_addr = buf;
 	descr->buf_size = skb->len;
+	descr->next_descr_addr = 0;
 	descr->skb = skb;
 	descr->data_status = 0;
 
-	spider_net_set_txdescr_cmdstat(descr,skb);
+	descr->dmac_cmd_status =
+			SPIDER_NET_DESCR_CARDOWNED | SPIDER_NET_DMAC_NOCS;
+	if (skb->protocol == htons(ETH_P_IP))
+		switch (skb->nh.iph->protocol) {
+		case IPPROTO_TCP:
+			descr->dmac_cmd_status |= SPIDER_NET_DMAC_TCP;
+			break;
+		case IPPROTO_UDP:
+			descr->dmac_cmd_status |= SPIDER_NET_DMAC_UDP;
+			break;
+		}
+
+	descr->prev->next_descr_addr = descr->bus_addr;
+
+	return 0;
+}
+
+/**
+ * spider_net_release_tx_descr - processes a used tx descriptor
+ * @card: card structure
+ * @descr: descriptor to release
+ *
+ * releases a used tx descriptor (unmapping, freeing of skb)
+ */
+static inline void
+spider_net_release_tx_descr(struct spider_net_card *card)
+{
+	struct spider_net_descr *descr = card->tx_chain.tail;
+	struct sk_buff *skb;
+
+	card->tx_chain.tail = card->tx_chain.tail->next;
+	descr->dmac_cmd_status |= SPIDER_NET_DESCR_NOT_IN_USE;
+
+	/* unmap the skb */
+	skb = descr->skb;
+	pci_unmap_single(card->pdev, descr->buf_addr, skb->len,
+			PCI_DMA_TODEVICE);
+	dev_kfree_skb_any(skb);
+}
+
+/**
+ * spider_net_release_tx_chain - processes sent tx descriptors
+ * @card: adapter structure
+ * @brutal: if set, don't care about whether descriptor seems to be in use
+ *
+ * returns 0 if the tx ring is empty, otherwise 1.
+ *
+ * spider_net_release_tx_chain releases the tx descriptors that spider has
+ * finished with (if non-brutal) or simply release tx descriptors (if brutal).
+ * If some other context is calling this function, we return 1 so that we're
+ * scheduled again (if we were scheduled) and will not loose initiative.
+ */
+static int
+spider_net_release_tx_chain(struct spider_net_card *card, int brutal)
+{
+	struct spider_net_descr_chain *chain = &card->tx_chain;
+	int status;
+
+	spider_net_read_reg(card, SPIDER_NET_GDTDMACCNTR);
+
+	while (chain->tail != chain->head) {
+		status = spider_net_get_descr_status(chain->tail);
+		switch (status) {
+		case SPIDER_NET_DESCR_COMPLETE:
+			card->netdev_stats.tx_packets++;
+			card->netdev_stats.tx_bytes += chain->tail->skb->len;
+			break;
+
+		case SPIDER_NET_DESCR_CARDOWNED:
+			if (!brutal)
+				return 1;
+			/* fallthrough, if we release the descriptors
+			 * brutally (then we don't care about
+			 * SPIDER_NET_DESCR_CARDOWNED) */
+
+		case SPIDER_NET_DESCR_RESPONSE_ERROR:
+		case SPIDER_NET_DESCR_PROTECTION_ERROR:
+		case SPIDER_NET_DESCR_FORCE_END:
+			if (netif_msg_tx_err(card))
+				pr_err("%s: forcing end of tx descriptor "
+				       "with status x%02x\n",
+				       card->netdev->name, status);
+			card->netdev_stats.tx_errors++;
+			break;
+
+		default:
+			card->netdev_stats.tx_dropped++;
+			return 1;
+		}
+		spider_net_release_tx_descr(card);
+	}
 
 	return 0;
 }
@@ -896,18 +763,32 @@ spider_net_prepare_tx_descr(struct spider_net_card *card,
  * spider_net_kick_tx_dma writes the current tx chain head as start address
  * of the tx descriptor chain and enables the transmission DMA engine
  */
-static void
-spider_net_kick_tx_dma(struct spider_net_card *card,
-		       struct spider_net_descr *descr)
+static inline void
+spider_net_kick_tx_dma(struct spider_net_card *card)
 {
-	/* this is the only descriptor in the output chain.
-	 * Enable TX DMA */
+	struct spider_net_descr *descr;
 
-	spider_net_write_reg(card, SPIDER_NET_GDTDCHA,
-			     descr->bus_addr);
+	if (spider_net_read_reg(card, SPIDER_NET_GDTDMACCNTR) &
+			SPIDER_NET_TX_DMA_EN)
+		goto out;
 
-	spider_net_write_reg(card, SPIDER_NET_GDTDMACCNTR,
-			     SPIDER_NET_DMA_TX_VALUE);
+	descr = card->tx_chain.tail;
+	for (;;) {
+		if (spider_net_get_descr_status(descr) ==
+				SPIDER_NET_DESCR_CARDOWNED) {
+			spider_net_write_reg(card, SPIDER_NET_GDTDCHA,
+					descr->bus_addr);
+			spider_net_write_reg(card, SPIDER_NET_GDTDMACCNTR,
+					SPIDER_NET_DMA_TX_VALUE);
+			break;
+		}
+		if (descr == card->tx_chain.head)
+			break;
+		descr = descr->next;
+	}
+
+out:
+	mod_timer(&card->tx_timer, jiffies + SPIDER_NET_TX_TIMER);
 }
 
 /**
@@ -915,47 +796,69 @@ spider_net_kick_tx_dma(struct spider_net_card *card,
  * @skb: packet to send out
  * @netdev: interface device structure
  *
- * returns 0 on success, <0 on failure
+ * returns 0 on success, !0 on failure
  */
 static int
 spider_net_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct spider_net_card *card = netdev_priv(netdev);
-	struct spider_net_descr *descr;
+	struct spider_net_descr_chain *chain = &card->tx_chain;
+	struct spider_net_descr *descr = chain->head;
+	unsigned long flags;
 	int result;
 
+	spin_lock_irqsave(&chain->lock, flags);
+
 	spider_net_release_tx_chain(card, 0);
 
-	descr = spider_net_get_next_tx_descr(card);
+	if (chain->head->next == chain->tail->prev) {
+		card->netdev_stats.tx_dropped++;
+		result = NETDEV_TX_LOCKED;
+		goto out;
+	}
 
-	if (!descr)
-		goto error;
+	if (spider_net_get_descr_status(descr) != SPIDER_NET_DESCR_NOT_IN_USE) {
+		result = NETDEV_TX_LOCKED;
+		goto out;
+	}
 
-	result = spider_net_prepare_tx_descr(card, descr, skb);
-	if (result)
-		goto error;
+	if (spider_net_prepare_tx_descr(card, skb) != 0) {
+		card->netdev_stats.tx_dropped++;
+		result = NETDEV_TX_BUSY;
+		goto out;
+	}
+
+	result = NETDEV_TX_OK;
 
+	spider_net_kick_tx_dma(card);
 	card->tx_chain.head = card->tx_chain.head->next;
 
-	if (spider_net_get_descr_status(descr->prev) !=
-	    SPIDER_NET_DESCR_CARDOWNED) {
-		/* make sure the current descriptor is in memory. Then
-		 * kicking it on again makes sense, if the previous is not
-		 * card-owned anymore. Check the previous descriptor twice
-		 * to omit an mb() in heavy traffic cases */
-		mb();
-		if (spider_net_get_descr_status(descr->prev) !=
-		    SPIDER_NET_DESCR_CARDOWNED)
-			spider_net_kick_tx_dma(card, descr);
-	}
+out:
+	spin_unlock_irqrestore(&chain->lock, flags);
+	netif_wake_queue(netdev);
+	return result;
+}
 
-	mod_timer(&card->tx_timer, jiffies + SPIDER_NET_TX_TIMER);
+/**
+ * spider_net_cleanup_tx_ring - cleans up the TX ring
+ * @card: card structure
+ *
+ * spider_net_cleanup_tx_ring is called by the tx_timer (as we don't use
+ * interrupts to cleanup our TX ring) and returns sent packets to the stack
+ * by freeing them
+ */
+static void
+spider_net_cleanup_tx_ring(struct spider_net_card *card)
+{
+	unsigned long flags;
 
-	return NETDEV_TX_OK;
+	spin_lock_irqsave(&card->tx_chain.lock, flags);
 
-error:
-	card->netdev_stats.tx_dropped++;
-	return NETDEV_TX_BUSY;
+	if ((spider_net_release_tx_chain(card, 0) != 0) &&
+	    (card->netdev->flags & IFF_UP))
+		spider_net_kick_tx_dma(card);
+
+	spin_unlock_irqrestore(&card->tx_chain.lock, flags);
 }
 
 /**
@@ -1002,7 +905,7 @@ spider_net_pass_skb_up(struct spider_net_descr *descr,
 
 	/* unmap descriptor */
 	pci_unmap_single(card->pdev, descr->buf_addr, SPIDER_NET_MAX_FRAME,
-			 PCI_DMA_BIDIRECTIONAL);
+			PCI_DMA_FROMDEVICE);
 
 	/* the cases we'll throw away the packet immediately */
 	if (data_error & SPIDER_NET_DESTROY_RX_FLAGS) {
@@ -1067,14 +970,11 @@ spider_net_pass_skb_up(struct spider_net_descr *descr,
 static int
 spider_net_decode_one_descr(struct spider_net_card *card, int napi)
 {
-	enum spider_net_descr_status status;
-	struct spider_net_descr *descr;
-	struct spider_net_descr_chain *chain;
+	struct spider_net_descr_chain *chain = &card->rx_chain;
+	struct spider_net_descr *descr = chain->tail;
+	int status;
 	int result;
 
-	chain = &card->rx_chain;
-	descr = chain->tail;
-
 	status = spider_net_get_descr_status(descr);
 
 	if (status == SPIDER_NET_DESCR_CARDOWNED) {
@@ -1103,7 +1003,7 @@ spider_net_decode_one_descr(struct spider_net_card *card, int napi)
 			       card->netdev->name, status);
 		card->netdev_stats.rx_dropped++;
 		pci_unmap_single(card->pdev, descr->buf_addr,
-				 SPIDER_NET_MAX_FRAME, PCI_DMA_BIDIRECTIONAL);
+				SPIDER_NET_MAX_FRAME, PCI_DMA_FROMDEVICE);
 		dev_kfree_skb_irq(descr->skb);
 		goto refill;
 	}
@@ -1119,7 +1019,7 @@ spider_net_decode_one_descr(struct spider_net_card *card, int napi)
 	/* ok, we've got a packet in descr */
 	result = spider_net_pass_skb_up(descr, card, napi);
 refill:
-	spider_net_set_descr_status(descr, SPIDER_NET_DESCR_NOT_IN_USE);
+	descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
 	/* change the descriptor state: */
 	if (!napi)
 		spider_net_refill_rx_chain(card);
@@ -1291,21 +1191,6 @@ spider_net_set_mac(struct net_device *netdev, void *p)
 }
 
 /**
- * spider_net_enable_txdmac - enables a TX DMA controller
- * @card: card structure
- *
- * spider_net_enable_txdmac enables the TX DMA controller by setting the
- * descriptor chain tail address
- */
-static void
-spider_net_enable_txdmac(struct spider_net_card *card)
-{
-	/* assume chain is aligned correctly */
-	spider_net_write_reg(card, SPIDER_NET_GDTDCHA,
-			     card->tx_chain.tail->bus_addr);
-}
-
-/**
  * spider_net_handle_rxram_full - cleans up RX ring upon RX RAM full interrupt
  * @card: card structure
  *
@@ -1653,7 +1538,6 @@ spider_net_enable_card(struct spider_net_card *card)
 		{ SPIDER_NET_GMRWOLCTRL, 0 },
 		{ SPIDER_NET_GTESTMD, 0x10000000 },
 		{ SPIDER_NET_GTTQMSK, 0x00400040 },
-		{ SPIDER_NET_GTESTMD, 0 },
 
 		{ SPIDER_NET_GMACINTEN, 0 },
 
@@ -1692,9 +1576,6 @@ spider_net_enable_card(struct spider_net_card *card)
 
 	spider_net_write_reg(card, SPIDER_NET_GRXDMAEN, SPIDER_NET_WOL_VALUE);
 
-	/* set chain tail adress for TX chain */
-	spider_net_enable_txdmac(card);
-
 	spider_net_write_reg(card, SPIDER_NET_GMACLENLMT,
 			     SPIDER_NET_LENLMT_VALUE);
 	spider_net_write_reg(card, SPIDER_NET_GMACMODE,
@@ -1709,6 +1590,9 @@ spider_net_enable_card(struct spider_net_card *card)
 			     SPIDER_NET_INT1_MASK_VALUE);
 	spider_net_write_reg(card, SPIDER_NET_GHIINT2MSK,
 			     SPIDER_NET_INT2_MASK_VALUE);
+
+	spider_net_write_reg(card, SPIDER_NET_GDTDMACCNTR,
+			     SPIDER_NET_GDTDCEIDIS);
 }
 
 /**
@@ -1728,10 +1612,12 @@ spider_net_open(struct net_device *netdev)
 
 	result = -ENOMEM;
 	if (spider_net_init_chain(card, &card->tx_chain,
-			  card->descr, tx_descriptors))
+			card->descr,
+			PCI_DMA_TODEVICE, tx_descriptors))
 		goto alloc_tx_failed;
 	if (spider_net_init_chain(card, &card->rx_chain,
-			  card->descr + tx_descriptors, rx_descriptors))
+			card->descr + tx_descriptors,
+			PCI_DMA_FROMDEVICE, rx_descriptors))
 		goto alloc_rx_failed;
 
 	/* allocate rx skbs */
@@ -1955,6 +1841,49 @@ spider_net_workaround_rxramfull(struct spider_net_card *card)
 }
 
 /**
+ * spider_net_stop - called upon ifconfig down
+ * @netdev: interface device structure
+ *
+ * always returns 0
+ */
+int
+spider_net_stop(struct net_device *netdev)
+{
+	struct spider_net_card *card = netdev_priv(netdev);
+
+	tasklet_kill(&card->rxram_full_tl);
+	netif_poll_disable(netdev);
+	netif_carrier_off(netdev);
+	netif_stop_queue(netdev);
+	del_timer_sync(&card->tx_timer);
+
+	/* disable/mask all interrupts */
+	spider_net_write_reg(card, SPIDER_NET_GHIINT0MSK, 0);
+	spider_net_write_reg(card, SPIDER_NET_GHIINT1MSK, 0);
+	spider_net_write_reg(card, SPIDER_NET_GHIINT2MSK, 0);
+
+	/* free_irq(netdev->irq, netdev);*/
+	free_irq(to_pci_dev(netdev->class_dev.dev)->irq, netdev);
+
+	spider_net_write_reg(card, SPIDER_NET_GDTDMACCNTR,
+			     SPIDER_NET_DMA_TX_FEND_VALUE);
+
+	/* turn off DMA, force end */
+	spider_net_disable_rxdmac(card);
+
+	/* release chains */
+	if (spin_trylock(&card->tx_chain.lock)) {
+		spider_net_release_tx_chain(card, 1);
+		spin_unlock(&card->tx_chain.lock);
+	}
+
+	spider_net_free_chain(card, &card->tx_chain);
+	spider_net_free_chain(card, &card->rx_chain);
+
+	return 0;
+}
+
+/**
  * spider_net_tx_timeout_task - task scheduled by the watchdog timeout
  * function (to be called not under interrupt status)
  * @data: data, is interface device structure
@@ -1982,7 +1911,7 @@ spider_net_tx_timeout_task(void *data)
 		goto out;
 
 	spider_net_open(netdev);
-	spider_net_kick_tx_dma(card, card->tx_chain.head);
+	spider_net_kick_tx_dma(card);
 	netif_device_attach(netdev);
 
 out:
@@ -2065,7 +1994,6 @@ spider_net_setup_netdev(struct spider_net_card *card)
 
 	pci_set_drvdata(card->pdev, netdev);
 
-	atomic_set(&card->tx_chain_release,0);
 	card->rxram_full_tl.data = (unsigned long) card;
 	card->rxram_full_tl.func =
 		(void (*)(unsigned long)) spider_net_handle_rxram_full;
@@ -2079,7 +2007,7 @@ spider_net_setup_netdev(struct spider_net_card *card)
 
 	spider_net_setup_netdev_ops(netdev);
 
-	netdev->features = NETIF_F_HW_CSUM;
+	netdev->features = NETIF_F_HW_CSUM | NETIF_F_LLTX;
 	/* some time: NETIF_F_HW_VLAN_TX | NETIF_F_HW_VLAN_RX |
 	 *		NETIF_F_HW_VLAN_FILTER */