[PATCH 2/2 2.6.6-rc1-bk5] pcnet32 timer to free tx skbs for 79C971/972

[Don Fry <brazilnut@xxxxxxxxxx>]

At the next opportunity to add new code to 2.6.6, please apply the following:

This patch uses an on-chip timer to free completed transmit skb's for the
79C971 and 972 versions which currently will leave completed transmit
skb's on the transmit ring until new transmit traffic occurs.

--- linux-2.6.6-rc1-bk5/drivers/net/dump.pcnet32.c      Tue Apr 20 15:47:47 2004
+++ linux-2.6.6-rc1-bk5/drivers/net/pcnet32.c   Tue Apr 20 15:48:49 2004
@@ -237,6 +237,8 @@
  *        Thomas Munck Steenholdt <tmus@xxxxxxx> non-mii ioctl corrections.
  * v1.29   6 Apr 2004 Jim Lewis <jklewis@xxxxxxxxxx> added physical
  *        identification code (blink led's) and register dump.
+ *        Don Fry added timer for 971/972 so skbufs don't remain on tx ring
+ *        forever.
  */
 
 
@@ -497,9 +499,9 @@
 #ifdef CONFIG_NET_POLL_CONTROLLER
 static void pcnet32_poll_controller(struct net_device *dev)
 {
-       disable_irq(dev->irq);
-       pcnet32_interrupt(0, dev, NULL);
-       enable_irq(dev->irq);
+    disable_irq(dev->irq);
+    pcnet32_interrupt(0, dev, NULL);
+    enable_irq(dev->irq);
 }
 #endif
 
@@ -1105,6 +1107,13 @@
        ltint = 1;
     }
 
+    if (ltint) {
+       /* Enable timer to prevent skbuffs from remaining on the tx ring
+        * forever if no other tx being done.  Set timer period to about
+        * 122 ms */
+       a->write_bcr(ioaddr, 31, 0x253b);
+    }
+
     dev = alloc_etherdev(0);
     if (!dev) {
        if (pcnet32_debug & NETIF_MSG_PROBE)
@@ -1451,6 +1460,11 @@
     lp->a.write_csr (ioaddr, 4, 0x0915);
     lp->a.write_csr (ioaddr, 0, 0x0001);
 
+    if (lp->ltint) {
+       /* start the software timer */
+       lp->a.write_csr(ioaddr, 7, 0x0400);     /* set STINTE */
+    }
+
     netif_start_queue(dev);
 
     /* If we have mii, print the link status and start the watchdog */
@@ -1652,13 +1666,13 @@
     int entry;
     unsigned long flags;
 
+    spin_lock_irqsave(&lp->lock, flags);
+
     if (netif_msg_tx_queued(lp)) {
        printk(KERN_DEBUG "%s: pcnet32_start_xmit() called, csr0 %4.4x.\n",
               dev->name, lp->a.read_csr(ioaddr, 0));
     }
 
-    spin_lock_irqsave(&lp->lock, flags);
-
     /* Default status -- will not enable Successful-TxDone
      * interrupt when that option is available to us.
      */
@@ -1719,7 +1733,7 @@
     struct net_device *dev = dev_id;
     struct pcnet32_private *lp;
     unsigned long ioaddr;
-    u16 csr0,rap;
+    u16 csr0, csr7, rap;
     int boguscnt =  max_interrupt_work;
     int must_restart;
 
@@ -1736,13 +1750,19 @@
     spin_lock(&lp->lock);
 
     rap = lp->a.read_rap(ioaddr);
-    while ((csr0 = lp->a.read_csr (ioaddr, 0)) & 0x8600 && --boguscnt >= 0) {
+    csr0 = lp->a.read_csr (ioaddr, 0);
+    csr7 = lp->ltint ? lp->a.read_csr(ioaddr, 7) : 0;
+
+    while ((csr0 & 0x8600 || csr7 & 0x0800) && --boguscnt >= 0) {
        if (csr0 == 0xffff) {
            break;                      /* PCMCIA remove happened */
        }
        /* Acknowledge all of the current interrupt sources ASAP. */
        lp->a.write_csr (ioaddr, 0, csr0 & ~0x004f);
 
+       if (csr7 & 0x0800)
+           lp->a.write_csr(ioaddr, 7, csr7);
+
        must_restart = 0;
 
        if (netif_msg_intr(lp))
@@ -1752,7 +1772,7 @@
        if (csr0 & 0x0400)              /* Rx interrupt */
            pcnet32_rx(dev);
 
-       if (csr0 & 0x0200) {            /* Tx-done interrupt */
+       if (csr0 & 0x0200 || csr7 & 0x0800) {   /* Tx-done or Timer interrupt */
            unsigned int dirty_tx = lp->dirty_tx;
            int delta;
 
@@ -1859,6 +1879,9 @@
            lp->a.write_csr (ioaddr, 0, 0x0004);
            pcnet32_restart(dev, 0x0002);
        }
+
+       csr0 = lp->a.read_csr (ioaddr, 0);
+       csr7 = lp->ltint ? lp->a.read_csr(ioaddr, 7) : 0;
     }
 
     /* Clear any other interrupt, and set interrupt enable. */
@@ -1945,6 +1968,7 @@
                    if (i > RX_RING_SIZE -2) {
                        lp->stats.rx_dropped++;
                        lp->rx_ring[entry].status |= le16_to_cpu(0x8000);
+                       wmb();  /* Make sure adapter sees owner change */
                        lp->cur_rx++;
                    }
                    break;
@@ -2008,6 +2032,10 @@
     /* We stop the PCNET32 here -- it occasionally polls memory if we don't. */
     lp->a.write_csr (ioaddr, 0, 0x0004);
 
+    if (lp->ltint) {   /* Disable timer interrupts */
+       lp->a.write_csr(ioaddr, 7, 0x0000);
+    }
+
     /*
      * Switch back to 16bit mode to avoid problems with dumb
      * DOS packet driver after a warm reboot
@@ -2018,9 +2046,12 @@
 
     free_irq(dev->irq, dev);
 
+    spin_lock_irqsave(&lp->lock, flags);
+
     /* free all allocated skbuffs */
     for (i = 0; i < RX_RING_SIZE; i++) {
        lp->rx_ring[i].status = 0;
+       wmb();          /* Make sure adapter sees owner change */
        if (lp->rx_skbuff[i]) {
            pci_unmap_single(lp->pci_dev, lp->rx_dma_addr[i], PKT_BUF_SZ-2,
                    PCI_DMA_FROMDEVICE);
@@ -2031,6 +2062,8 @@
     }
 
     for (i = 0; i < TX_RING_SIZE; i++) {
+       lp->tx_ring[i].status = 0;      /* CPU owns buffer */
+       wmb();          /* Make sure adapter sees owner change */
        if (lp->tx_skbuff[i]) {
            pci_unmap_single(lp->pci_dev, lp->tx_dma_addr[i],
                    lp->tx_skbuff[i]->len, PCI_DMA_TODEVICE);
@@ -2040,6 +2073,8 @@
        lp->tx_dma_addr[i] = 0;
     }
 
+    spin_unlock_irqrestore(&lp->lock, flags);
+
     return 0;
 }
 

-- 
Don Fry
brazilnut@xxxxxxxxxx