Subject: MPC8xx IDMA and console garbage

From: Steven Scholz <[email-masked]>
Date: Tue, 23 Apr 2002 13:37:34 +0200

Hi there,

I am trying to get DMA support for MPC8xx IDE. For now I use the IDMA
channel.
It is kind of working although it's not much more than a framework yet.

BUT:

My problem right now is this:

After activating the DMA (e.g. using hdparm -d1 /dev/hda) the output of
my serial console (connected to SMC1) gets garbaged when there is HDD
activity.

If I telnet into my machine and do e.g. a "fdisk -l /dev/hda" the output
of the serial console looks something like this

^PttyS: 80 input overrun(s)
 ^P^P^P^P^P^P^P^P^P^ ^PP ^ ^PP ^ ^PP ^P ^P^P^P^P^P^P ^P
^P^P^P^P^P^P^P^P^P^P^P^P^PttyS: 80 input overrun(s)

If I redirect console input into a file it contains 0x10 and 0x20 bytes.

So someone is flooding the serial port (SMC) with the two byte 0x10 and
0x20 !
(I might have seen 0x10 and 0xA0 as well.)

Any ideas?

Could there be a problem in using the internal ram area. Maybe my IDMA
is conflicting with anyother existing driver (SMC???) ?

Thanks,

Steven

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