Fix an error that was causing Tx to timeout improperly

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1639 42af7a65-404d-4744-a932-0658087f49c3

ChangeLog

@@ -662,5 +662,9 @@
 	* net/uip: Correct UDP bind behavior.  It should select a valid port number
 	  if it receives a port number of zero.
 	* netutils/dhcpd:  Corrrect for ZDS compiler.  Fix issue with re-use of a
-	  port number. Fix a number of broadcast-related problems.
+	  port number. Fixed a number of broadcast-related problems.
 	* eZ80Acclaim!: Add a tiny webserver configuration
+	* eZ80Acclaim!: Fixed an important bug in the EMAC Tx timeout logic. It was
+	  always timing out when the load was heavy and worse, for some reason,
+	  resetting the Tx function caused unexpected registers to be reset in
+	  the Rcv function was well.

Documentation/NuttX.html

@@ -8,7 +8,7 @@
   <tr align="center" bgcolor="#e4e4e4">
     <td>
       <h1><big><font color="#3c34ec"><i>NuttX RTOS</i></font></big></h1>
-      <p>Last Updated: March 21, 2009</p>
+      <p>Last Updated: March 22, 2009</p>
     </td>
   </tr>
 </table>
@@ -1353,8 +1353,12 @@ nuttx-0.4.4 2009-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 	* net/uip: Correct UDP bind behavior.  It should select a valid port number
 	  if it receives a port number of zero.
 	* netutils/dhcpd:  Corrrect for ZDS compiler.  Fix issue with re-use of a
-	  port number.  Fix a number of broadcast-related problems.
+	  port number.  Fixed a number of broadcast-related problems.
 	* eZ80Acclaim!: Add a tiny webserver configuration
+	* eZ80Acclaim!: Fixed an important bug in the EMAC Tx timeout logic. It was
+	  always timing out when the load was heavy and worse, for some reason,
+	  resetting the Tx function caused unexpected registers to be reset in
+	  the Rcv function was well.
 
 pascal-0.1.3 2009-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 

arch/z80/src/ez80/ez80_emac.c

@@ -276,7 +276,7 @@ struct ez80emac_driver_s
    *            Tx/Rx memory).
    * txhead:    Points to the oldest Tx descriptor queued for output (but for
    *            which output has not yet completed.  Initialized to NULL; set
-   *            by ez80emac_transmit() when Tx is started and by ez80emac_reclaimtxdesc()
+   *            by ez80emac_transmit() when Tx is started and by ez80emac_txinterrupt()
    *            when Tx processing completes.  txhead == NULL is also a sure
    *            indication that there is no Tx in progress.
    * txnext:    Points to the next free Tx descriptor. Initialized to txstart; set
@@ -946,7 +946,7 @@ static int ez80emac_transmit(struct ez80emac_driver_s *priv)
    * handler and, therefore, may be suspended when debug output is generated!
    */
 
-  nllvdbg("ENTRY: txnext=%p {%06x, %u, %04x} trp=%02x%02x\n",
+  nllvdbg("txnext=%p {%06x, %u, %04x} trp=%02x%02x\n",
           priv->txnext, priv->txnext->np, priv->txnext->pktsize, priv->txnext->stat,
           inp(EZ80_EMAC_TRP_H), inp(EZ80_EMAC_TRP_L));
 
@@ -1025,7 +1025,7 @@ static int ez80emac_transmit(struct ez80emac_driver_s *priv)
   outp(EZ80_EMAC_PTMR, EMAC_PTMR);
   irqrestore(flags);
 
-  nllvdbg("EXIT: txdesc=%p {%06x, %u, %04x}\n",
+  nllvdbg("txdesc=%p {%06x, %u, %04x}\n",
           txdesc, txdesc->np, txdesc->pktsize, txdesc->stat);
   nllvdbg("txnext=%p {%06x, %u, %04x} trp=%02x%02x\n",
           txnext, txnext->np, txnext->pktsize, txnext->stat,
@@ -1323,7 +1323,7 @@ static int ez80emac_receive(struct ez80emac_driver_s *priv)
 static int ez80emac_txinterrupt(int irq, FAR void *context)
 {
   FAR struct ez80emac_driver_s *priv = &g_emac;
-  FAR struct ez80emac_desc_s *txdesc = priv->txhead;
+  FAR struct ez80emac_desc_s *txhead = priv->txhead;
   ubyte regval;
   ubyte istat;
 
@@ -1340,31 +1340,23 @@ static int ez80emac_txinterrupt(int irq, FAR void *context)
   istat = inp(EZ80_EMAC_ISTAT) & EMAC_ISTAT_TXEVENTS;
   outp(EZ80_EMAC_ISTAT, istat);
 
+  EMAC_STAT(priv, tx_int);
+
   /* All events are packet/control frame transmit complete events */
 
   nvdbg("txhead=%p {%06x, %u, %04x} trp=%02x%02x istat=%02x\n",
-        txdesc, txdesc->np, txdesc->pktsize, txdesc->stat,
+        txhead, txhead->np, txhead->pktsize, txhead->stat,
         inp(EZ80_EMAC_TRP_H), inp(EZ80_EMAC_TRP_L), istat);
 
-  EMAC_STAT(priv, tx_int);
+  /* Handle all packets in the list that are no longer owned by the hardware */
 
-  /* Check if the packet is still owned by the hardware */
+  while (txhead && (txhead->stat & EMAC_TXDESC_OWNER) == 0)
-
-  if ((txdesc->stat & EMAC_TXDESC_OWNER) != 0)
     {
-      ndbg("Descriptor %p still owned by H/W {%06x, %u, %04x} trp=%02x%02x istat=%02x\n",
+      if ((txhead->stat & EMAC_TXDESC_ABORT) != 0)
-           txdesc, txdesc->np, txdesc->pktsize, txdesc->stat,
-           inp(EZ80_EMAC_TRP_H), inp(EZ80_EMAC_TRP_L), istat);
-      return OK;
-    }
-
-  /* Handle errors */
-
-  else if ((txdesc->stat & EMAC_TXDESC_ABORT) != 0)
         {
-      ndbg("Descriptor %p aborted {%06x, %u, %04x} trp=%02x%02x istat=%02x\n",
+          ndbg("Descriptor %p aborted {%06x, %u, %04x} trp=%02x%02x\n",
-           txdesc, txdesc->np, txdesc->pktsize, txdesc->stat,
+               txhead, txhead->np, txhead->pktsize, txhead->stat,
-           inp(EZ80_EMAC_TRP_H), inp(EZ80_EMAC_TRP_L), istat);
+               inp(EZ80_EMAC_TRP_H), inp(EZ80_EMAC_TRP_L));
 
           EMAC_STAT(priv, tx_errors);
           EMAC_STAT(priv, tx_abterrors);
@@ -1372,43 +1364,49 @@ static int ez80emac_txinterrupt(int irq, FAR void *context)
 
       /* Get the address of the next Tx descriptor in the list (if any) */
 
-  priv->txhead = (FAR struct ez80emac_desc_s *)txdesc->np;
+      txhead = (FAR struct ez80emac_desc_s *)txhead->np;
+      if (txhead)
+        {
+          nvdbg("txhead=%p {%06x, %u, %04x} trp=%02x%02x\n",
+                txhead, txhead->np, txhead->pktsize, txhead->stat,
+                inp(EZ80_EMAC_TRP_H), inp(EZ80_EMAC_TRP_L));
+        }
+    }
+
+  /* Save the new head.  If it is NULL, then we have read all the way to 
+   * the terminating description with np==NULL.
+   */
+
+  priv->txhead = txhead;
   if (!priv->txhead)
     {
-      /* No pending TX -- This should never happen because there
+      nvdbg("No pending Tx.. Stopping XMIT function.\n");
-       * is always a dummy descriptor at the end of the list owned
+      
-       * by the host.  Reset to the beginining of the buffer
+      /* Stop the Tx poll timer. (It will get restarted when we have
-       * and stop the poll timer
+       * something to send
        */
 
       outp(EZ80_EMAC_PTMR, 0);
-      priv->txnext = priv->txstart;
 
       /* Reset the transmit function.  That should force the TRP to be
-       * the same as TDLP which is the set to txstart.
+       * the same as TDLP which is then set to txstart.
        */
 
+#if 0 // Seems to reset RWP as well ???
+      priv->txnext = priv->txstart;
+
       regval = inp(EZ80_EMAC_RST);
       regval |= EMAC_RST_HRTFN;
       outp(EZ80_EMAC_RST, regval);
       regval &= ~EMAC_RST_HRTFN;
       outp(EZ80_EMAC_RST, regval);
+#endif
 
-      /* If no further xmits are pending, then cancel the TX timeout */
+      /* Cancel any pending the TX timeout */
 
       wd_cancel(priv->txtimeout);
     }
  
-  /* Clean up the old Tx descriptor -- not really necessary */
-
-  txdesc->np      = 0;
-  txdesc->pktsize = 0;
-  txdesc->stat    = 0;
-
-  nvdbg("New txhead=%p {%06x, %u, %04x} trp=%02x%02x istat=%02x\n",
-        priv->txhead, priv->txhead->np, priv->txhead->pktsize, priv->txhead->stat,
-        inp(EZ80_EMAC_TRP_H), inp(EZ80_EMAC_TRP_L), istat);
- 
   return OK;
 }