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MPC8313e DMA problem with more than 40 bytes

Question asked by Juan Antonio Medina Guerrero on May 19, 2009
Latest reply on May 21, 2009 by Juan Antonio Medina Guerrero

I use DMA to read from PCI.

 

- The buffer is reserved by kmalloc and aligned to the size of the page

- I limit the transmission to multiples of 8*4 bytes. I use a complete cache line.

- I used direct mode. Now I use chain mode to improve the transfer speed but It's not enough yet.

- I tried with 32, 40 and 48 bytes. When I use 48 bytes the system hangs. I don't see this limitation  anywhere.

 

any suggestions? Has anyone experienced similar problems with DMA? 

 

Thanks a lot in advance.

 

Regards,

Medina

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