alt_dma_txchan_send status

[Altera_Forum]

I am getting an error from alt_dma_txchan_send. The status returned is -22. Below is the code. I lifted this code from this forum http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif  

  alt_dma_txchan_open is successful, but the call to alt_dma_txchan_send returns a -22.  Any help is appreciated.  thanx   alt_32 flag;  alt_dma_txchan txchan;    if((txchan=alt_dma_txchan_open(dma_name))==NULL)  {  printf("\n Failed to open transmit channel(range-to-1)!\n");  //exit(1);  }  alt_dma_txchan_ioctl(txchan,transfer_mode,NULL);  alt_dma_txchan_ioctl(txchan,ALT_DMA_RX_STREAM_ON,start_addr);    if((flag=alt_dma_txchan_send(txchan,desti_addr,transfer_count,transmit_done,NULL ))<0)  {  printf("\n Failed to post transmit request(range-to-1)!\n");  //exit(1);  }    while(!transmitdone);  transmitdone=0;  alt_dma_txchan_ioctl(txchan,ALT_DMA_RX_STREAM_OFF,NULL);  //alt_dma_txchan_close(txchan);  }

[Altera_Forum]

Can you post your design of DMA here? Your code is good, but which transferring mode you are using here?

[Altera_Forum]

Thanx. Truth is, I lifted this code from this forum http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif  

 This line calls the dma function:  nr_dma_copy_range_to_1_nli("/dev/USB_DMA",(void *)txdata,(void *)usbdata, ByteCount, ALT_DMA_SET_MODE_8 );  Following is the whole routine it gets stuck in the while(!transmitdone) logic like the callback is never called......    /* ************************************************************************* */ /* The following routines is for range-to-1 processing. */ /* ************************************************************************* */ void nr_dma_copy_range_to_1_nli(const char* dma_name,  void* start_addr, //Here,start_addr is the "range"  void* desti_addr, //and desti_addr is the "1"  alt_32 transfer_count,  alt_32 transfer_mode) {  alt_32 flag;  alt_dma_txchan txchan;    if((txchan=alt_dma_txchan_open(dma_name))==NULL)  {  printf("\n Failed to open transmit channel(range-to-1)!\n");  //exit(1);  }  alt_dma_txchan_ioctl(txchan,transfer_mode,NULL);  alt_dma_txchan_ioctl(txchan,ALT_DMA_TX_STREAM_ON,start_addr);    if((flag=alt_dma_txchan_send(txchan,desti_addr,transfer_count,transmit_done,NULL ))<0)  {  printf("\n Failed to post transmit request(range-to-1)!\n");  //exit(1);  }    while(!transmitdone)  usleep(20);  transmitdone=0;  alt_dma_txchan_ioctl(txchan,ALT_DMA_RX_STREAM_OFF,NULL);  //alt_dma_txchan_close(txchan);  }

[Altera_Forum]

Perhaps you should use 

 alt_dma_txchan_ioctl(txchan,ALT_DMA_RX_STREAM_ON,start_addr);   instead of   alt_dma_txchan_ioctl(txchan,ALT_DMA_TX_STREAM_ON,start_addr);