PPC4xx : Failed to perform memory to memory DMA

Hi,

I  am using 2.6.23  kernel for ppc 440spe based board. When i tried memory to memory DMA  ( please find  the code given below )
DMA is not happening.

I am trying the same for last few days.... without any success.  Can any one guide me.

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////


#include<linux/kernel.h>
#include<linux/module.h>
#include<linux/delay.h>

#include<asm/ppc4xx_dma.h>
#include<asm/io.h>
#include<linux/slab.h>

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("PPC4xx Mem to Mem DMA  demo");
MODULE_AUTHOR("padmanabha@tesbv.com");

extern void flush_dcache_all(void);

#define DMA_CHANNEL_NUM                         0
#define SIZE                                                    4096

ppc_dma_ch_t  ppc_dma_channel;
ppc_dma_ch_t p_init;

void * vir_dst_addr;
void * vir_src_addr;

unsigned long int  phy_src;
unsigned long int  phy_dst;

int ret, offset;

void dma_trns(void)
{

   memset( (char *)&p_init, 0, sizeof(p_init));

   p_init.polarity = 0;
   p_init.pwidth   = PW_8;

   ret = ppc4xx_init_dma_channel( DMA_CHANNEL_NUM, &p_init);

   if (ret  ==   DMA_STATUS_GOOD)
   {
       printk("%s: init_dma_channel return %d, dest is %p\n",__FUNCTION__, ret, vir_dst_addr);
   }

   else if(ret  ==   DMA_STATUS_BAD_CHANNEL)
   {

     printk("TS2: bad channel \n");

   }

   flush_dcache_all();

   ppc4xx_clr_dma_status( DMA_CHANNEL_NUM);

   ppc4xx_set_dma_mode(DMA_CHANNEL_NUM,DMA_MODE_MM);
   ppc4xx_set_src_addr( DMA_CHANNEL_NUM, (phys_addr_t) phy_src);
   ppc4xx_set_dst_addr(DMA_CHANNEL_NUM,  (phys_addr_t) phy_dst);
   ppc4xx_set_dma_count(DMA_CHANNEL_NUM,(SIZE * 2 ));

   ppc4xx_set_channel_priority(DMA_CHANNEL_NUM,PRIORITY_HIGH);

   ppc4xx_enable_dma(DMA_CHANNEL_NUM);


   // wait till completion of DMA


    while( 1)
    {
         mdelay(100);

         ret = 1;
         ret = ppc4xx_get_dma_residue( DMA_CHANNEL_NUM);

         if( ret == 0)
         {
             printk(" no dma operation is pending\n");
             break;
         }

    }

  ppc4xx_disable_dma( DMA_CHANNEL_NUM);

 return  ;
}

static int dma_test_init(void)
{

 vir_src_addr = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, 1);

 if( vir_src_addr == NULL )
 {
     printk( " Memory not allocated\n");
     return 1;
 }
 printk("%s: virtual address for src buffer is 0x%p \n",__FUNCTION__, (unsigned int *)vir_src_addr);
 memset( (unsigned long *)vir_src_addr, 0x55, sizeof(unsigned long) * (SIZE *2));

#if SRC_DISPLAY

 ret = 0;

 while(ret < 100)
 {

     printk( "%s: value at virtual addr 0x%p is 0x%X \n", __FUNCTION__,( (unsigned int *)vir_src_addr + ret ),\

     *( (unsigned int *)vir_src_addr + ret));

     ret++;

 }

#endif

 vir_dst_addr = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA,1);

 if( vir_dst_addr == NULL )
 {
     printk( " Memory not allocated\n");
     free_pages( (unsigned long)vir_src_addr, 1);
     return 1;
 }
 printk("%s: virtual address for dst buffer is 0x%p \n",__FUNCTION__,(unsigned int *)vir_dst_addr);
 memset( (unsigned long *)vir_dst_addr, 0, sizeof(unsigned long) * (SIZE *2));

#if DST_DISPLAY

 ret = 0;
 while(ret < 100)
 {

     printk( "%s: value at virtual addr 0x%p is 0x%X \n", __FUNCTION__,( (unsigned int *)vir_dst_addr + ret ),\
     *( (unsigned int *)vir_dst_addr + ret));

     ret++;

 }
#endif

//      phy_src = virt_to_bus(vir_src_addr);
//      phy_dst = virt_to_bus(vir_dst_addr);

   phy_src = iopa( (unsigned long ) vir_src_addr);
   phy_dst =  iopa(  (unsigned long )vir_dst_addr);

 dma_trns();

   ret = 1;
   ret = ppc4xx_get_dma_residue( DMA_CHANNEL_NUM);
   if( ret == 0)
   {
       printk(" no dma operation is pending\n");

   }

 return 0;
}


void dma_test_exit(void)
{
   ret = ppc4xx_get_channel_config( DMA_CHANNEL_NUM, &ppc_dma_channel);

   if( ret != DMA_STATUS_GOOD )
   {
      printk("TS2: DMA STATUS  is not good \n");
   }
   else
   {
      printk("TS2:  DMA STATUS  good \n");

   }

   ret = 0;

   while(ret < 100)
   {

      printk( "%s: value at virtual addr 0x%p after dma is 0x%X \n", __FUNCTION__,( (unsigned int *)vir_dst_addr + ret ), \
      *( (unsigned int *)vir_dst_addr + ret)) ;

      ret++;
   }

  mdelay(100);

  free_pages( (unsigned long)vir_src_addr, 1);
  free_pages( (unsigned long)vir_dst_addr, 1);

}

module_init(dma_test_init);
module_exit(dma_test_exit);

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////


Thanks and Regards,
Padmanabha.s