DMA problem - mpc8xx

raul.moreno at raul.moreno at
Tue Oct 23 17:42:43 EST 2007

Hi everybody,

I am having problems with the serial cpm driver in a mpc866. But I've found
out that my problem comes from the DMA and not really from the driver.  The
Rx and Tx buffers use the DMA and then the sytem hangs. However, if I set
these buffers to internal ram memory (DPRAM), it works. The DMA address is
configured with a kernel parameter in advance setup:
don't know what they are exactly and I could not find a right documentation
about it.
I saw a pair of mailing list where some guys set the
CONFIG_CONSISTENT_START to 0xff100000, but my driver continues failing (and
an error about dma-mapping appears in the boot).

Did anyone have a similar problem?
Could anyone help me?

Thanks in advance,

Raúl Moreno

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