[PATCH] natsemi: NAPI and a bugfix

As documented in National application note 1287 the RX state machine on
the natsemi chip can lock up under some conditions (mostly related to
heavy load).  When this happens a series of bogus packets are reported
by the chip including some oversized frames prior to the final lockup.

This patch implements the fix from the application note: when an
oversized packet is reported it resets the RX state machine, dropping
any currently pending packets.

Signed-off-by: Mark Brown <broonie@sirena.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/drivers/net/natsemi.c b/drivers/net/natsemi.c
index e363f9bb35ea..8d4999837b65 100644
--- a/drivers/net/natsemi.c
+++ b/drivers/net/natsemi.c
@@ -1498,6 +1498,31 @@ static void natsemi_reset(struct net_device *dev)
         writel(rfcr, ioaddr + RxFilterAddr);
 }
 
+static void reset_rx(struct net_device *dev)
+{
+        int i;
+        struct netdev_private *np = netdev_priv(dev);
+        void __iomem *ioaddr = ns_ioaddr(dev);
+
+        np->intr_status &= ~RxResetDone;
+
+        writel(RxReset, ioaddr + ChipCmd);
+
+        for (i=0;i<NATSEMI_HW_TIMEOUT;i++) {
+                np->intr_status |= readl(ioaddr + IntrStatus);
+                if (np->intr_status & RxResetDone)
+                        break;
+                udelay(15);
+        }
+        if (i==NATSEMI_HW_TIMEOUT) {
+                printk(KERN_WARNING "%s: RX reset did not complete in %d usec.\n",
+                       dev->name, i*15);
+        } else if (netif_msg_hw(np)) {
+                printk(KERN_WARNING "%s: RX reset took %d usec.\n",
+                       dev->name, i*15);
+        }
+}
+
 static void natsemi_reload_eeprom(struct net_device *dev)
 {
         struct netdev_private *np = netdev_priv(dev);
@@ -2292,6 +2317,23 @@ static void netdev_rx(struct net_device *dev, int *work_done, int work_to_do)
                                                 "status %#08x.\n", dev->name,
                                                 np->cur_rx, desc_status);
                                 np->stats.rx_length_errors++;
+
+                                /* The RX state machine has probably
+                                 * locked up beneath us.  Follow the
+                                 * reset procedure documented in
+                                 * AN-1287. */
+
+                                spin_lock_irq(&np->lock);
+                                reset_rx(dev);
+                                reinit_rx(dev);
+                                writel(np->ring_dma, ioaddr + RxRingPtr);
+                                check_link(dev);
+                                spin_unlock_irq(&np->lock);
+
+                                /* We'll enable RX on exit from this
+                                 * function. */
+                                break;
+
                         } else {
                                 /* There was an error. */
                                 np->stats.rx_errors++;