Altera TSE driver and example program for lwIP (1.3.2)

Igor,

Building your program (changing it to NO_SYS=1 and no RTOS) doesn't download - some debugger complaint about running 2 programs? Anyway, adding echo.c to my version of the example does run and I can confirm your finding.

This is pretty bad - I don't know why I don't find this problem in real applications - even those using telnet. Anyway, you cannot send more bytes than required to meet the minimum 4 quantity. The only option is to copy the pbuf chains to a single pbuf. I think this sucks! But so it is. This works:

/* @Function Description -  TSE transmit API to send data to the MAC
 *
 *
 * @API TYPE - Public
 * @param  net  - NET structure associated with the TSE MAC instance
 * @param  data - pointer to the data payload
 * @param  data_bytes - number of bytes of the data payload to be sent to the MAC
 * @return SUCCESS if success, else a negative value
 */
err_t tse_mac_raw_send(struct netif *netif, struct pbuf *pkt)
{
   int                tx_length;
   unsigned           len;
   struct pbuf        *p, *q = NULL;
   alt_u32            *data;
   tse_mac_trans_info *mi;
   lwip_tse_info      *tse_ptr;
   struct ethernetif  *ethernetif;
   unsigned int       *ActualData;
   /* Intermediate buffers used for temporary copy of frames that cannot be directrly DMA'ed*/
   char buf2;
   ethernetif = netif->state;
   tse_ptr = ethernetif->tse_info;
   mi = &tse_ptr->mi;
   if(pkt->next != NULL)        // Unwind pbuf chains
       {
       q = pbuf_alloc(PBUF_RAW, pkt->tot_len, pkt->type);
       for(len = 0, p = pkt; p != NULL; p = p->next)
           {
           memcpy(q->payload + len, p->payload, p->len);
           len += p->len;
           }
       pkt = q;
       }
   for(p = pkt; p != NULL; p = p->next)
      {
      data = p->payload;
      len = p->len;
      if(((unsigned long)data & 0x03) != 0)
         {
         /*
          * Copy data to temporary buffer <buf2>. This is done because of allignment
          * issues. The SGDMA cannot copy the data directly from (data + ETH_PAD_SIZE)
          * because it needs a 32-bit alligned address space.
          */
         memcpy(buf2,data,len);
         data = (alt_u32 *)buf2;
         }
      ActualData = (void *)alt_remap_uncached (data, len<4 ? 4 : len);
      printf("<%d @ 0x%08X/0x%08X>", len, (unsigned int)p->payload, (unsigned int)ActualData);
      if(len<4)
          len=4;
      /* Write data to Tx FIFO using the DMA */
      alt_avalon_sgdma_construct_mem_to_stream_desc(
           (alt_sgdma_descriptor *) &tse_ptr->desc, // descriptor I want to work with
           (alt_sgdma_descriptor *) &tse_ptr->desc,// pointer to "next"
           (alt_u32*)ActualData,                    // starting read address
           (len),                                   //#  bytes
           0,                                       // don't read from constant address
           p == pkt,                                // generate sop
           p->next == NULL,                         // generate endofpacket signal
           0);                                      // atlantic channel (don't know/don't care: set to 0)
      tx_length = tse_mac_sTxWrite(mi,&tse_ptr->desc);
      ethernetif->bytes_sent += tx_length;
      }
   if(q != NULL)
       pbuf_free(q);
   LINK_STATS_INC(link.xmit);
   return ERR_OK;
}

You could optimize it by first checking if any chains are less than 4 and doing this addition only when one or more is, but I kept it simple - just do it if there are chains.

Maybe it's risky but I intend to not change my lwIP-based products. They don't show the problem which I don't know why. Maybe I could add this code and it would never be called???

[Update: Probably should check for q != NULL and exit if so. Of course this will result in errors as well!]

Bill