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Altera_Forum
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15 years ago

SGDMA descriptor list questions

I want to build a descriptor linked list to transfer data form memory to TSE MAC.If I build one descriptor there's no problem.If I build more than one descriptors no data was transfered.Is there anybody tell me why?

this is the code:

alt_avalon_sgdma_register_callback(pM_Context->mac_mi.tx_sgdma,

&sgdma_transmit_callback_function,

( ALTERA_AVALON_SGDMA_CONTROL_IE_GLOBAL_MSK |ALTERA_AVALON_SGDMA_CONTROL_IE_CHAIN_COMPLETED_MSK)

pM_Context);

for(i=0;i<ASYNC_TRANS_DESC_MAX;i++)//||

{

printf("config descrip \n");

p_write = pM_Context->Frame_List.Pbuffer[pM_Context->Frame_List.rear]+pM_Context->Frame_List.offset;

pM_Context->Frame_List.offset += pM_Context->Frame_List.packetsize;

pM_Context->Frame_List.framesubnum++;

//packet_length = pM_Context->Frame_List.packetsize;

alt_avalon_sgdma_construct_mem_to_stream_desc(&pM_Context->Current_desc[i], // descriptor

&pM_Context->Current_desc[i+1], // next descriptor

(alt_u32 *)p_write, // read buffer location

(pM_Context->Frame_List.packetsize), // length of the buffer

0, // reads are not from a fixed location

1, // start of packet is enabled for the Avalon-ST interfaces

1, // end of packet is enabled for the Avalon-ST interfaces,

0); // there is only one channel

}

alt_avalon_sgdma_do_async_transfer(pM_Context->mac_mi.tx_sgdma,

pM_Context->Current_desc);

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    for(tse_ptr->chain_loop = 0; tse_ptr->chain_loop < ALTERA_TSE_SGDMA_RX_DESC_CHAIN_SIZE; tse_ptr->chain_loop++)

    {

    tse_ptr->pkt_array[tse_ptr->chain_loop] = pk_alloc(ALTERA_TSE_PKT_INIT_LEN+4);

    if (!tse_ptr->pkt_array[tse_ptr->chain_loop]) /* couldn't get a free buffer for rx */

    {

    dprintf("[tse_sgdma_read_init] Fatal error: No free packet buffers for RX\n");

    tse_ptr->netp->n_mib->ifInDiscards++;

    return ENP_NOBUFFER;

    }

    // ensure bit-31 of tse_ptr->pkt_array[tse_ptr->chain_loop]->nb_buff is clear before passing

    // to SGDMA Driver

    uncached_packet_payload = (alt_u32 *)alt_remap_cached ((volatile void*) tse_ptr->pkt_array[tse_ptr->chain_loop]->nb_buff, 4);

    alt_avalon_sgdma_construct_stream_to_mem_desc(

    (alt_sgdma_descriptor *) &tse_ptr->desc[tse_ptr->chain_loop+ALTERA_TSE_FIRST_RX_SGDMA_DESC_OFST], // descriptor I want to work with

    (alt_sgdma_descriptor *) &tse_ptr->desc[tse_ptr->chain_loop+ALTERA_TSE_SECOND_RX_SGDMA_DESC_OFST], // pointer to "next"

    uncached_packet_payload, // tse_ptr->pkt_array[tse_ptr->chain_loop]->nb_buff, // starting write_address

    0, // read until EOP

    0); // don't write to constant address

    }

    I find the code in the TSE MAC IP.