MPC8313e DMA problem with more than 40 bytes

medina — Tue, 19 May 2009 15:02:56 GMT

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

Re: MPC8313e DMA problem with more than 40 bytes

medina — Thu, 21 May 2009 22:53:01 GMT

Sorry, but in my previous message there was an error. When I wrote "32, 40 and 48 byte" I meant "32*4, 40*4 and 48*4 bytes".

Regards,

Medina