[PATCH] spidernet: performance optimizations

Performance optimizations, changes in these areas:
  - RX and TX checksum offload
  - correct maximum MTU
  - don't use TX interrupts anymore, use a timer instead
  - remove some superfluous barriers
  - improve RX RAM full handling

From: Utz Bacher <utz.bacher@de.ibm.com>
Signed-off-by: Jens Osterkamp <jens.osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 248 insertions, 249 deletions

diff --git a/drivers/net/spider_net.c b/drivers/net/spider_net.c
index 86969191c3f7..e2ad9aef0109 100644
--- a/drivers/net/spider_net.c
+++ b/drivers/net/spider_net.c
@@ -22,7 +22,6 @@
  */
 
 #include <linux/config.h>
-
 #include <linux/compiler.h>
 #include <linux/crc32.h>
 #include <linux/delay.h>
@@ -43,6 +42,7 @@
 #include <linux/slab.h>
 #include <linux/tcp.h>
 #include <linux/types.h>
+#include <linux/vmalloc.h>
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 #include <asm/bitops.h>
@@ -108,42 +108,6 @@ spider_net_write_reg(struct spider_net_card *card, u32 reg, u32 value)
         writel(value, card->regs + reg);
 }
 
-/**
- * spider_net_write_reg_sync - writes to an SMMIO register of a card
- * @card: device structure
- * @reg: register to write to
- * @value: value to write into the specified SMMIO register
- *
- * Unlike spider_net_write_reg, this will also make sure the
- * data arrives on the card by reading the reg again.
- */
-static void
-spider_net_write_reg_sync(struct spider_net_card *card, u32 reg, u32 value)
-{
-        value = cpu_to_le32(value);
-        writel(value, card->regs + reg);
-        (void)readl(card->regs + reg);
-}
-
-/**
- * spider_net_rx_irq_off - switch off rx irq on this spider card
- * @card: device structure
- *
- * switches off rx irq by masking them out in the GHIINTnMSK register
- */
-static void
-spider_net_rx_irq_off(struct spider_net_card *card)
-{
-        u32 regvalue;
-        unsigned long flags;
-
-        spin_lock_irqsave(&card->intmask_lock, flags);
-        regvalue = spider_net_read_reg(card, SPIDER_NET_GHIINT0MSK);
-        regvalue &= ~SPIDER_NET_RXINT;
-        spider_net_write_reg_sync(card, SPIDER_NET_GHIINT0MSK, regvalue);
-        spin_unlock_irqrestore(&card->intmask_lock, flags);
-}
-
 /** spider_net_write_phy - write to phy register
  * @netdev: adapter to be written to
  * @mii_id: id of MII
@@ -199,60 +163,33 @@ spider_net_read_phy(struct net_device *netdev, int mii_id, int reg)
 }
 
 /**
- * spider_net_rx_irq_on - switch on rx irq on this spider card
- * @card: device structure
- *
- * switches on rx irq by enabling them in the GHIINTnMSK register
- */
-static void
-spider_net_rx_irq_on(struct spider_net_card *card)
-{
-        u32 regvalue;
-        unsigned long flags;
-
-        spin_lock_irqsave(&card->intmask_lock, flags);
-        regvalue = spider_net_read_reg(card, SPIDER_NET_GHIINT0MSK);
-        regvalue |= SPIDER_NET_RXINT;
-        spider_net_write_reg_sync(card, SPIDER_NET_GHIINT0MSK, regvalue);
-        spin_unlock_irqrestore(&card->intmask_lock, flags);
-}
-
-/**
- * spider_net_tx_irq_off - switch off tx irq on this spider card
+ * spider_net_rx_irq_off - switch off rx irq on this spider card
  * @card: device structure
  *
- * switches off tx irq by masking them out in the GHIINTnMSK register
+ * switches off rx irq by masking them out in the GHIINTnMSK register
  */
 static void
-spider_net_tx_irq_off(struct spider_net_card *card)
+spider_net_rx_irq_off(struct spider_net_card *card)
 {
         u32 regvalue;
-        unsigned long flags;
 
-        spin_lock_irqsave(&card->intmask_lock, flags);
-        regvalue = spider_net_read_reg(card, SPIDER_NET_GHIINT0MSK);
-        regvalue &= ~SPIDER_NET_TXINT;
-        spider_net_write_reg_sync(card, SPIDER_NET_GHIINT0MSK, regvalue);
-        spin_unlock_irqrestore(&card->intmask_lock, flags);
+        regvalue = SPIDER_NET_INT0_MASK_VALUE & (~SPIDER_NET_RXINT);
+        spider_net_write_reg(card, SPIDER_NET_GHIINT0MSK, regvalue);
 }
 
 /**
- * spider_net_tx_irq_on - switch on tx irq on this spider card
+ * spider_net_rx_irq_on - switch on rx irq on this spider card
  * @card: device structure
  *
- * switches on tx irq by enabling them in the GHIINTnMSK register
+ * switches on rx irq by enabling them in the GHIINTnMSK register
  */
 static void
-spider_net_tx_irq_on(struct spider_net_card *card)
+spider_net_rx_irq_on(struct spider_net_card *card)
 {
         u32 regvalue;
-        unsigned long flags;
 
-        spin_lock_irqsave(&card->intmask_lock, flags);
-        regvalue = spider_net_read_reg(card, SPIDER_NET_GHIINT0MSK);
-        regvalue |= SPIDER_NET_TXINT;
-        spider_net_write_reg_sync(card, SPIDER_NET_GHIINT0MSK, regvalue);
-        spin_unlock_irqrestore(&card->intmask_lock, flags);
+        regvalue = SPIDER_NET_INT0_MASK_VALUE | SPIDER_NET_RXINT;
+        spider_net_write_reg(card, SPIDER_NET_GHIINT0MSK, regvalue);
 }
 
 /**
@@ -326,9 +263,8 @@ static enum spider_net_descr_status
 spider_net_get_descr_status(struct spider_net_descr *descr)
 {
         u32 cmd_status;
-        rmb();
+
         cmd_status = descr->dmac_cmd_status;
-        rmb();
         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) */
@@ -349,7 +285,6 @@ spider_net_set_descr_status(struct spider_net_descr *descr,
 {
         u32 cmd_status;
         /* read the status */
-        mb();
         cmd_status = descr->dmac_cmd_status;
         /* clean the upper 4 bits */
         cmd_status &= SPIDER_NET_DESCR_IND_PROC_MASKO;
@@ -357,7 +292,6 @@ spider_net_set_descr_status(struct spider_net_descr *descr,
         cmd_status |= ((u32)status)<<SPIDER_NET_DESCR_IND_PROC_SHIFT;
         /* and write it back */
         descr->dmac_cmd_status = cmd_status;
-        wmb();
 }
 
 /**
@@ -398,8 +332,9 @@ spider_net_init_chain(struct spider_net_card *card,
 {
         int i;
         struct spider_net_descr *descr;
+        dma_addr_t buf;
 
-        spin_lock_init(&card->chain_lock);
+        atomic_set(&card->rx_chain_refill,0);
 
         descr = start_descr;
         memset(descr, 0, sizeof(*descr) * no);
@@ -408,14 +343,14 @@ spider_net_init_chain(struct spider_net_card *card,
         for (i=0; i<no; i++, descr++) {
                 spider_net_set_descr_status(descr, SPIDER_NET_DESCR_NOT_IN_USE);
 
-                descr->bus_addr =
-                        pci_map_single(card->pdev, descr,
-                                       SPIDER_NET_DESCR_SIZE,
-                                       PCI_DMA_BIDIRECTIONAL);
+                buf = pci_map_single(card->pdev, descr,
+                                     SPIDER_NET_DESCR_SIZE,
+                                     PCI_DMA_BIDIRECTIONAL);
 
-                if (descr->bus_addr == DMA_ERROR_CODE)
+                if (buf == DMA_ERROR_CODE)
                         goto iommu_error;
 
+                descr->bus_addr = buf;
                 descr->next = descr + 1;
                 descr->prev = descr - 1;
 
@@ -439,7 +374,8 @@ iommu_error:
         for (i=0; i < no; i++, descr++)
                 if (descr->bus_addr)
                         pci_unmap_single(card->pdev, descr->bus_addr,
-                                         SPIDER_NET_DESCR_SIZE, PCI_DMA_BIDIRECTIONAL);
+                                         SPIDER_NET_DESCR_SIZE,
+                                         PCI_DMA_BIDIRECTIONAL);
         return -ENOMEM;
 }
 
@@ -459,7 +395,7 @@ spider_net_free_rx_chain_contents(struct spider_net_card *card)
                 if (descr->skb) {
                         dev_kfree_skb(descr->skb);
                         pci_unmap_single(card->pdev, descr->buf_addr,
-                                         SPIDER_NET_MAX_MTU,
+                                         SPIDER_NET_MAX_FRAME,
                                          PCI_DMA_BIDIRECTIONAL);
                 }
                 descr = descr->next;
@@ -486,7 +422,7 @@ spider_net_prepare_rx_descr(struct spider_net_card *card,
         int bufsize;
 
         /* we need to round up the buffer size to a multiple of 128 */
-        bufsize = (SPIDER_NET_MAX_MTU + SPIDER_NET_RXBUF_ALIGN - 1) &
+        bufsize = (SPIDER_NET_MAX_FRAME + SPIDER_NET_RXBUF_ALIGN - 1) &
                 (~(SPIDER_NET_RXBUF_ALIGN - 1));
 
         /* and we need to have it 128 byte aligned, therefore we allocate a
@@ -494,10 +430,8 @@ spider_net_prepare_rx_descr(struct spider_net_card *card,
         /* allocate an skb */
         descr->skb = dev_alloc_skb(bufsize + SPIDER_NET_RXBUF_ALIGN - 1);
         if (!descr->skb) {
-                if (net_ratelimit())
-                        if (netif_msg_rx_err(card))
-                                pr_err("Not enough memory to allocate "
-                                        "rx buffer\n");
+                if (netif_msg_rx_err(card) && net_ratelimit())
+                        pr_err("Not enough memory to allocate rx buffer\n");
                 return -ENOMEM;
         }
         descr->buf_size = bufsize;
@@ -512,12 +446,11 @@ 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_MTU,
-                                         PCI_DMA_BIDIRECTIONAL);
+                             SPIDER_NET_MAX_FRAME, PCI_DMA_BIDIRECTIONAL);
         descr->buf_addr = buf;
         if (buf == DMA_ERROR_CODE) {
                 dev_kfree_skb_any(descr->skb);
-                if (netif_msg_rx_err(card))
+                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);
         } else {
@@ -528,10 +461,10 @@ spider_net_prepare_rx_descr(struct spider_net_card *card,
 }
 
 /**
- * spider_net_enable_rxctails - sets RX dmac chain tail addresses
+ * spider_net_enable_rxchtails - sets RX dmac chain tail addresses
  * @card: card structure
  *
- * spider_net_enable_rxctails sets the RX DMAC chain tail adresses in the
+ * spider_net_enable_rxchtails sets the RX DMAC chain tail adresses in the
  * chip by writing to the appropriate register. DMA is enabled in
  * spider_net_enable_rxdmac.
  */
@@ -553,6 +486,7 @@ spider_net_enable_rxchtails(struct spider_net_card *card)
 static void
 spider_net_enable_rxdmac(struct spider_net_card *card)
 {
+        wmb();
         spider_net_write_reg(card, SPIDER_NET_GDADMACCNTR,
                              SPIDER_NET_DMA_RX_VALUE);
 }
@@ -561,32 +495,28 @@ spider_net_enable_rxdmac(struct spider_net_card *card)
  * spider_net_refill_rx_chain - refills descriptors/skbs in the rx chains
  * @card: card structure
  *
- * refills descriptors in all chains (last used chain first): allocates skbs
- * and iommu-maps them.
+ * refills descriptors in the rx chain: allocates skbs and iommu-maps them.
  */
 static void
 spider_net_refill_rx_chain(struct spider_net_card *card)
 {
         struct spider_net_descr_chain *chain;
-        int count = 0;
-        unsigned long flags;
 
         chain = &card->rx_chain;
 
-        spin_lock_irqsave(&card->chain_lock, flags);
-        while (spider_net_get_descr_status(chain->head) ==
-                                SPIDER_NET_DESCR_NOT_IN_USE) {
-                if (spider_net_prepare_rx_descr(card, chain->head))
-                        break;
-                count++;
-                chain->head = chain->head->next;
-        }
-        spin_unlock_irqrestore(&card->chain_lock, 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;
+                }
 
-        /* could be optimized, only do that, if we know the DMA processing
-         * has terminated */
-        if (count)
-                spider_net_enable_rxdmac(card);
+        atomic_dec(&card->rx_chain_refill);
 }
 
 /**
@@ -615,6 +545,7 @@ spider_net_alloc_rx_skbs(struct spider_net_card *card)
         /* this will allocate the rest of the rx buffers; if not, it's
          * business as usual later on */
         spider_net_refill_rx_chain(card);
+        spider_net_enable_rxdmac(card);
         return 0;
 
 error:
@@ -651,24 +582,30 @@ spider_net_release_tx_descr(struct spider_net_card *card,
  * @card: adapter structure
  * @brutal: if set, don't care about whether descriptor seems to be in use
  *
- * releases the tx descriptors that spider has finished with (if non-brutal)
- * or simply release tx descriptors (if brutal)
+ * 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 void
+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;
 
-        spider_net_tx_irq_off(card);
+        if (atomic_inc_return(&card->tx_chain_release) != 1) {
+                atomic_dec(&card->tx_chain_release);
+                return 1;
+        }
 
-        /* no lock for chain needed, if this is only executed once at a time */
-again:
         for (;;) {
                 status = spider_net_get_descr_status(tx_chain->tail);
                 switch (status) {
                 case SPIDER_NET_DESCR_CARDOWNED:
-                        if (!brutal) goto out;
+                        if (!brutal)
+                                goto out;
                         /* fallthrough, if we release the descriptors
                          * brutally (then we don't care about
                          * SPIDER_NET_DESCR_CARDOWNED) */
@@ -695,25 +632,30 @@ again:
                 tx_chain->tail = tx_chain->tail->next;
         }
 out:
+        atomic_dec(&card->tx_chain_release);
+
         netif_wake_queue(card->netdev);
 
-        if (!brutal) {
-                /* switch on tx irqs (while we are still in the interrupt
-                 * handler, so we don't get an interrupt), check again
-                 * for done descriptors. This results in fewer interrupts */
-                spider_net_tx_irq_on(card);
-                status = spider_net_get_descr_status(tx_chain->tail);
-                switch (status) {
-                        case SPIDER_NET_DESCR_RESPONSE_ERROR:
-                        case SPIDER_NET_DESCR_PROTECTION_ERROR:
-                        case SPIDER_NET_DESCR_FORCE_END:
-                        case SPIDER_NET_DESCR_COMPLETE:
-                                goto again;
-                        default:
-                                break;
-                }
-        }
+        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);
+        }
 }
 
 /**
@@ -728,16 +670,22 @@ out:
 static u8
 spider_net_get_multicast_hash(struct net_device *netdev, __u8 *addr)
 {
-        /* FIXME: an addr of 01:00:5e:00:00:01 must result in 0xa9,
-         * ff:ff:ff:ff:ff:ff must result in 0xfd */
         u32 crc;
         u8 hash;
+        char addr_for_crc[ETH_ALEN] = { 0, };
+        int i, bit;
+
+        for (i = 0; i < ETH_ALEN * 8; i++) {
+                bit = (addr[i / 8] >> (i % 8)) & 1;
+                addr_for_crc[ETH_ALEN - 1 - i / 8] += bit << (7 - (i % 8));
+        }
 
-        crc = crc32_be(~0, addr, netdev->addr_len);
+        crc = crc32_be(~0, addr_for_crc, netdev->addr_len);
 
         hash = (crc >> 27);
         hash <<= 3;
         hash |= crc & 7;
+        hash &= 0xff;
 
         return hash;
 }
@@ -823,9 +771,11 @@ 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);
@@ -874,13 +824,15 @@ spider_net_get_next_tx_descr(struct spider_net_card *card)
  * @skb: packet to consider
  *
  * fills out the command and status field of the descriptor structure,
- * depending on hardware checksum settings. This function assumes a wmb()
- * has executed before.
+ * 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;
@@ -889,14 +841,13 @@ spider_net_set_txdescr_cmdstat(struct spider_net_descr *descr,
         /* is packet ip?
          * if yes: tcp? udp? */
         if (skb->protocol == htons(ETH_P_IP)) {
-                if (skb->nh.iph->protocol == IPPROTO_TCP) {
+                if (skb->nh.iph->protocol == IPPROTO_TCP)
                         descr->dmac_cmd_status = SPIDER_NET_DMAC_CMDSTAT_TCPCS;
-                } else if (skb->nh.iph->protocol == IPPROTO_UDP) {
+                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 */
+                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;
-                }
         }
 }
 
@@ -916,10 +867,12 @@ spider_net_prepare_tx_descr(struct spider_net_card *card,
                             struct spider_net_descr *descr,
                             struct sk_buff *skb)
 {
-        dma_addr_t buf = pci_map_single(card->pdev, skb->data,
-                                        skb->len, PCI_DMA_BIDIRECTIONAL);
+        dma_addr_t buf;
+
+        buf = pci_map_single(card->pdev, skb->data,
+                             skb->len, PCI_DMA_BIDIRECTIONAL);
         if (buf == DMA_ERROR_CODE) {
-                if (netif_msg_tx_err(card))
+                if (netif_msg_tx_err(card) && net_ratelimit())
                         pr_err("could not iommu-map packet (%p, %i). "
                                   "Dropping packet\n", skb->data, skb->len);
                 return -ENOMEM;
@@ -930,10 +883,6 @@ spider_net_prepare_tx_descr(struct spider_net_card *card,
         descr->skb = skb;
         descr->data_status = 0;
 
-        /* make sure the above values are in memory before we change the
-         * status */
-        wmb();
-
         spider_net_set_txdescr_cmdstat(descr,skb);
 
         return 0;
@@ -975,17 +924,12 @@ spider_net_xmit(struct sk_buff *skb, struct net_device *netdev)
         struct spider_net_descr *descr;
         int result;
 
-        descr = spider_net_get_next_tx_descr(card);
+        spider_net_release_tx_chain(card, 0);
 
-        if (!descr) {
-                netif_stop_queue(netdev);
+        descr = spider_net_get_next_tx_descr(card);
 
-                descr = spider_net_get_next_tx_descr(card);
-                if (!descr)
-                        goto error;
-                else
-                        netif_start_queue(netdev);
-        }
+        if (!descr)
+                goto error;
 
         result = spider_net_prepare_tx_descr(card, descr, skb);
         if (result)
@@ -993,19 +937,25 @@ spider_net_xmit(struct sk_buff *skb, struct net_device *netdev)
 
         card->tx_chain.head = card->tx_chain.head->next;
 
-        /* make sure the status from spider_net_prepare_tx_descr is in
-         * memory before we check out the previous descriptor */
-        wmb();
-
         if (spider_net_get_descr_status(descr->prev) !=
-            SPIDER_NET_DESCR_CARDOWNED)
-                spider_net_kick_tx_dma(card, descr);
+            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);
+        }
+
+        mod_timer(&card->tx_timer, jiffies + SPIDER_NET_TX_TIMER);
 
         return NETDEV_TX_OK;
 
 error:
         card->netdev_stats.tx_dropped++;
-        return NETDEV_TX_LOCKED;
+        return NETDEV_TX_BUSY;
 }
 
 /**
@@ -1030,6 +980,7 @@ spider_net_do_ioctl(struct net_device *netdev, struct ifreq *ifr, int cmd)
  * spider_net_pass_skb_up - takes an skb from a descriptor and passes it on
  * @descr: descriptor to process
  * @card: card structure
+ * @napi: whether caller is in NAPI context
  *
  * returns 1 on success, 0 if no packet was passed to the stack
  *
@@ -1038,7 +989,7 @@ spider_net_do_ioctl(struct net_device *netdev, struct ifreq *ifr, int cmd)
  */
 static int
 spider_net_pass_skb_up(struct spider_net_descr *descr,
-                       struct spider_net_card *card)
+                       struct spider_net_card *card, int napi)
 {
         struct sk_buff *skb;
         struct net_device *netdev;
@@ -1049,22 +1000,20 @@ spider_net_pass_skb_up(struct spider_net_descr *descr,
 
         netdev = card->netdev;
 
-        /* check for errors in the data_error flag */
-        if ((data_error & SPIDER_NET_DATA_ERROR_MASK) &&
-            netif_msg_rx_err(card))
-                pr_err("error in received descriptor found, "
-                       "data_status=x%08x, data_error=x%08x\n",
-                       data_status, data_error);
-
-        /* prepare skb, unmap descriptor */
-        skb = descr->skb;
-        pci_unmap_single(card->pdev, descr->buf_addr, SPIDER_NET_MAX_MTU,
+        /* unmap descriptor */
+        pci_unmap_single(card->pdev, descr->buf_addr, SPIDER_NET_MAX_FRAME,
                          PCI_DMA_BIDIRECTIONAL);
 
         /* the cases we'll throw away the packet immediately */
-        if (data_error & SPIDER_NET_DESTROY_RX_FLAGS)
+        if (data_error & SPIDER_NET_DESTROY_RX_FLAGS) {
+                if (netif_msg_rx_err(card))
+                        pr_err("error in received descriptor found, "
+                               "data_status=x%08x, data_error=x%08x\n",
+                               data_status, data_error);
                 return 0;
+        }
 
+        skb = descr->skb;
         skb->dev = netdev;
         skb_put(skb, descr->valid_size);
 
@@ -1076,14 +1025,14 @@ spider_net_pass_skb_up(struct spider_net_descr *descr,
 
         /* checksum offload */
         if (card->options.rx_csum) {
-                if ( (data_status & SPIDER_NET_DATA_STATUS_CHK_MASK) &&
-                     (!(data_error & SPIDER_NET_DATA_ERROR_CHK_MASK)) )
+                if ( ( (data_status & SPIDER_NET_DATA_STATUS_CKSUM_MASK) ==
+                       SPIDER_NET_DATA_STATUS_CKSUM_MASK) &&
+                     !(data_error & SPIDER_NET_DATA_ERR_CKSUM_MASK))
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
                 else
                         skb->ip_summed = CHECKSUM_NONE;
-        } else {
+        } else
                 skb->ip_summed = CHECKSUM_NONE;
-        }
 
         if (data_status & SPIDER_NET_VLAN_PACKET) {
                 /* further enhancements: HW-accel VLAN
@@ -1092,7 +1041,10 @@ spider_net_pass_skb_up(struct spider_net_descr *descr,
         }
 
         /* pass skb up to stack */
-        netif_receive_skb(skb);
+        if (napi)
+                netif_receive_skb(skb);
+        else
+                netif_rx_ni(skb);
 
         /* update netdevice statistics */
         card->netdev_stats.rx_packets++;
@@ -1102,16 +1054,18 @@ spider_net_pass_skb_up(struct spider_net_descr *descr,
 }
 
 /**
- * spider_net_decode_descr - processes an rx descriptor
+ * spider_net_decode_one_descr - processes an rx descriptor
  * @card: card structure
+ * @napi: whether caller is in NAPI context
  *
  * returns 1 if a packet has been sent to the stack, otherwise 0
  *
  * processes an rx descriptor by iommu-unmapping the data buffer and passing
- * the packet up to the stack
+ * the packet up to the stack. This function is called in softirq
+ * context, e.g. either bottom half from interrupt or NAPI polling context
  */
 static int
-spider_net_decode_one_descr(struct spider_net_card *card)
+spider_net_decode_one_descr(struct spider_net_card *card, int napi)
 {
         enum spider_net_descr_status status;
         struct spider_net_descr *descr;
@@ -1125,17 +1079,19 @@ spider_net_decode_one_descr(struct spider_net_card *card)
 
         if (status == SPIDER_NET_DESCR_CARDOWNED) {
                 /* nothing in the descriptor yet */
-                return 0;
+                result=0;
+                goto out;
         }
 
         if (status == SPIDER_NET_DESCR_NOT_IN_USE) {
-                /* not initialized yet, I bet chain->tail == chain->head
-                 * and the ring is empty */
+                /* not initialized yet, the ring must be empty */
                 spider_net_refill_rx_chain(card);
-                return 0;
+                spider_net_enable_rxdmac(card);
+                result=0;
+                goto out;
         }
 
-        /* descriptor definitively used -- move on head */
+        /* descriptor definitively used -- move on tail */
         chain->tail = descr->next;
 
         result = 0;
@@ -1146,6 +1102,9 @@ spider_net_decode_one_descr(struct spider_net_card *card)
                         pr_err("%s: dropping RX descriptor with state %d\n",
                                card->netdev->name, status);
                 card->netdev_stats.rx_dropped++;
+                pci_unmap_single(card->pdev, descr->buf_addr,
+                                 SPIDER_NET_MAX_FRAME, PCI_DMA_BIDIRECTIONAL);
+                dev_kfree_skb_irq(descr->skb);
                 goto refill;
         }
 
@@ -1158,12 +1117,13 @@ spider_net_decode_one_descr(struct spider_net_card *card)
         }
 
         /* ok, we've got a packet in descr */
-        result = spider_net_pass_skb_up(descr, card);
+        result = spider_net_pass_skb_up(descr, card, napi);
 refill:
         spider_net_set_descr_status(descr, SPIDER_NET_DESCR_NOT_IN_USE);
         /* change the descriptor state: */
-        spider_net_refill_rx_chain(card);
-
+        if (!napi)
+                spider_net_refill_rx_chain(card);
+out:
         return result;
 }
 
@@ -1189,7 +1149,7 @@ spider_net_poll(struct net_device *netdev, int *budget)
         packets_to_do = min(*budget, netdev->quota);
 
         while (packets_to_do) {
-                if (spider_net_decode_one_descr(card)) {
+                if (spider_net_decode_one_descr(card, 1)) {
                         packets_done++;
                         packets_to_do--;
                 } else {
@@ -1201,6 +1161,7 @@ spider_net_poll(struct net_device *netdev, int *budget)
 
         netdev->quota -= packets_done;
         *budget -= packets_done;
+        spider_net_refill_rx_chain(card);
 
         /* if all packets are in the stack, enable interrupts and return 0 */
         /* if not, return 1 */
@@ -1345,6 +1306,24 @@ spider_net_enable_txdmac(struct spider_net_card *card)
 }
 
 /**
+ * spider_net_handle_rxram_full - cleans up RX ring upon RX RAM full interrupt
+ * @card: card structure
+ *
+ * spider_net_handle_rxram_full empties the RX ring so that spider can put
+ * more packets in it and empty its RX RAM. This is called in bottom half
+ * context
+ */
+static void
+spider_net_handle_rxram_full(struct spider_net_card *card)
+{
+        while (spider_net_decode_one_descr(card, 0))
+                ;
+        spider_net_enable_rxchtails(card);
+        spider_net_enable_rxdmac(card);
+        netif_rx_schedule(card->netdev);
+}
+
+/**
  * spider_net_handle_error_irq - handles errors raised by an interrupt
  * @card: card structure
  * @status_reg: interrupt status register 0 (GHIINT0STS)
@@ -1452,17 +1431,21 @@ spider_net_handle_error_irq(struct spider_net_card *card, u32 status_reg)
                                 switch (i)
         {
         case SPIDER_NET_GTMFLLINT:
-                if (netif_msg_intr(card))
+                if (netif_msg_intr(card) && net_ratelimit())
                         pr_err("Spider TX RAM full\n");
                 show_error = 0;
                 break;
+        case SPIDER_NET_GRFDFLLINT: /* fallthrough */
+        case SPIDER_NET_GRFCFLLINT: /* fallthrough */
+        case SPIDER_NET_GRFBFLLINT: /* fallthrough */
+        case SPIDER_NET_GRFAFLLINT: /* fallthrough */
         case SPIDER_NET_GRMFLLINT:
-                if (netif_msg_intr(card))
+                if (netif_msg_intr(card) && net_ratelimit())
                         pr_err("Spider RX RAM full, incoming packets "
-                               "might be discarded !\n");
-                netif_rx_schedule(card->netdev);
-                spider_net_enable_rxchtails(card);
-                spider_net_enable_rxdmac(card);
+                               "might be discarded!\n");
+                spider_net_rx_irq_off(card);
+                tasklet_schedule(&card->rxram_full_tl);
+                show_error = 0;
                 break;
 
         /* case SPIDER_NET_GTMSHTINT: problem, print a message */
@@ -1470,10 +1453,6 @@ spider_net_handle_error_irq(struct spider_net_card *card, u32 status_reg)
                 /* allrighty. tx from previous descr ok */
                 show_error = 0;
                 break;
-        /* case SPIDER_NET_GRFDFLLINT: print a message down there */
-        /* case SPIDER_NET_GRFCFLLINT: print a message down there */
-        /* case SPIDER_NET_GRFBFLLINT: print a message down there */
-        /* case SPIDER_NET_GRFAFLLINT: print a message down there */
 
         /* chain end */
         case SPIDER_NET_GDDDCEINT: /* fallthrough */
@@ -1485,6 +1464,7 @@ spider_net_handle_error_irq(struct spider_net_card *card, u32 status_reg)
                                "restarting DMAC %c.\n",
                                'D'+i-SPIDER_NET_GDDDCEINT);
                 spider_net_refill_rx_chain(card);
+                spider_net_enable_rxdmac(card);
                 show_error = 0;
                 break;
 
@@ -1495,6 +1475,7 @@ spider_net_handle_error_irq(struct spider_net_card *card, u32 status_reg)
         case SPIDER_NET_GDAINVDINT:
                 /* could happen when rx chain is full */
                 spider_net_refill_rx_chain(card);
+                spider_net_enable_rxdmac(card);
                 show_error = 0;
                 break;
 
@@ -1583,17 +1564,13 @@ spider_net_interrupt(int irq, void *ptr, struct pt_regs *regs)
         if (!status_reg)
                 return IRQ_NONE;
 
-        if (status_reg & SPIDER_NET_TXINT)
-                spider_net_release_tx_chain(card, 0);
-
         if (status_reg & SPIDER_NET_RXINT ) {
                 spider_net_rx_irq_off(card);
                 netif_rx_schedule(netdev);
         }
 
-        /* we do this after rx and tx processing, as we want the tx chain
-         * processed to see, whether we should restart tx dma processing */
-        spider_net_handle_error_irq(card, status_reg);
+        if (status_reg & SPIDER_NET_ERRINT )
+                spider_net_handle_error_irq(card, status_reg);
 
         /* clear interrupt sources */
         spider_net_write_reg(card, SPIDER_NET_GHIINT0STS, status_reg);
@@ -1834,26 +1811,27 @@ spider_net_setup_phy(struct spider_net_card *card)
 /**
  * spider_net_download_firmware - loads firmware into the adapter
  * @card: card structure
- * @firmware: firmware pointer
+ * @firmware_ptr: pointer to firmware data
  *
- * spider_net_download_firmware loads the firmware opened by
- * spider_net_init_firmware into the adapter.
+ * spider_net_download_firmware loads the firmware data into the
+ * adapter. It assumes the length etc. to be allright.
  */
 static int
 spider_net_download_firmware(struct spider_net_card *card,
-                             const struct firmware *firmware)
+                             u8 *firmware_ptr)
 {
         int sequencer, i;
-        u32 *fw_ptr = (u32 *)firmware->data;
+        u32 *fw_ptr = (u32 *)firmware_ptr;
 
         /* stop sequencers */
         spider_net_write_reg(card, SPIDER_NET_GSINIT,
                              SPIDER_NET_STOP_SEQ_VALUE);
 
-        for (sequencer = 0; sequencer < 6; sequencer++) {
+        for (sequencer = 0; sequencer < SPIDER_NET_FIRMWARE_SEQS;
+             sequencer++) {
                 spider_net_write_reg(card,
                                      SPIDER_NET_GSnPRGADR + sequencer * 8, 0);
-                for (i = 0; i < SPIDER_NET_FIRMWARE_LEN; i++) {
+                for (i = 0; i < SPIDER_NET_FIRMWARE_SEQWORDS; i++) {
                         spider_net_write_reg(card, SPIDER_NET_GSnPRGDAT +
                                              sequencer * 8, *fw_ptr);
                         fw_ptr++;
@@ -1898,41 +1876,53 @@ spider_net_download_firmware(struct spider_net_card *card,
 static int
 spider_net_init_firmware(struct spider_net_card *card)
 {
-        struct firmware *firmware;
+        struct firmware *firmware = NULL;
         struct device_node *dn;
-        u8 *fw_prop;
-        int err = -EIO;
+        u8 *fw_prop = NULL;
+        int err = -ENOENT;
+        int fw_size;
 
         if (request_firmware((const struct firmware **)&firmware,
-                             SPIDER_NET_FIRMWARE_NAME, &card->pdev->dev) < 0) {
-                if (netif_msg_probe(card))
-                        pr_err("Couldn't read in sequencer data file %s.\n",
-                               SPIDER_NET_FIRMWARE_NAME);
-
-                dn = pci_device_to_OF_node(card->pdev);
-                if (!dn)
-                        goto out;
+                             SPIDER_NET_FIRMWARE_NAME, &card->pdev->dev) == 0) {
+                if ( (firmware->size != SPIDER_NET_FIRMWARE_LEN) &&
+                     netif_msg_probe(card) ) {
+                        pr_err("Incorrect size of spidernet firmware in " \
+                               "filesystem. Looking in host firmware...\n");
+                        goto try_host_fw;
+                }
+                err = spider_net_download_firmware(card, firmware->data);
 
-                fw_prop = (u8 *)get_property(dn, "firmware", NULL);
-                if (!fw_prop)
-                        goto out;
+                release_firmware(firmware);
+                if (err)
+                        goto try_host_fw;
 
-                memcpy(firmware->data, fw_prop, 6 * SPIDER_NET_FIRMWARE_LEN * sizeof(u32));
-                firmware->size = 6 * SPIDER_NET_FIRMWARE_LEN * sizeof(u32);
+                goto done;
         }
 
-        if (firmware->size != 6 * SPIDER_NET_FIRMWARE_LEN * sizeof(u32)) {
-                if (netif_msg_probe(card))
-                        pr_err("Invalid size of sequencer data file %s.\n",
-                               SPIDER_NET_FIRMWARE_NAME);
-                goto out;
+try_host_fw:
+        dn = pci_device_to_OF_node(card->pdev);
+        if (!dn)
+                goto out_err;
+
+        fw_prop = (u8 *)get_property(dn, "firmware", &fw_size);
+        if (!fw_prop)
+                goto out_err;
+
+        if ( (fw_size != SPIDER_NET_FIRMWARE_LEN) &&
+             netif_msg_probe(card) ) {
+                pr_err("Incorrect size of spidernet firmware in " \
+                       "host firmware\n");
+                goto done;
         }
 
-        if (!spider_net_download_firmware(card, firmware))
-                err = 0;
-out:
-        release_firmware(firmware);
+        err = spider_net_download_firmware(card, fw_prop);
 
+done:
+        return err;
+out_err:
+        if (netif_msg_probe(card))
+                pr_err("Couldn't find spidernet firmware in filesystem " \
+                       "or host firmware\n");
         return err;
 }
 
@@ -1952,10 +1942,11 @@ spider_net_workaround_rxramfull(struct spider_net_card *card)
                              SPIDER_NET_CKRCTRL_RUN_VALUE);
 
         /* empty sequencer data */
-        for (sequencer = 0; sequencer < 6; sequencer++) {
+        for (sequencer = 0; sequencer < SPIDER_NET_FIRMWARE_SEQS;
+             sequencer++) {
                 spider_net_write_reg(card, SPIDER_NET_GSnPRGDAT +
                                      sequencer * 8, 0x0);
-                for (i = 0; i < SPIDER_NET_FIRMWARE_LEN; i++) {
+                for (i = 0; i < SPIDER_NET_FIRMWARE_SEQWORDS; i++) {
                         spider_net_write_reg(card, SPIDER_NET_GSnPRGDAT +
                                              sequencer * 8, 0x0);
                 }
@@ -2079,7 +2070,15 @@ spider_net_setup_netdev(struct spider_net_card *card)
         SET_NETDEV_DEV(netdev, &card->pdev->dev);
 
         pci_set_drvdata(card->pdev, netdev);
-        spin_lock_init(&card->intmask_lock);
+
+        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;
+        init_timer(&card->tx_timer);
+        card->tx_timer.function =
+                (void (*)(unsigned long)) spider_net_cleanup_tx_ring;
+        card->tx_timer.data = (unsigned long) card;
         netdev->irq = card->pdev->irq;
 
         card->options.rx_csum = SPIDER_NET_RX_CSUM_DEFAULT;