PCI Timing issues oldworld w/G4 upgrade

[Robert Serphillips]

Seems to be some issues with the damsound modules when using either a
PCI nic or a PCI scsi card, in a PM8500 with a G4 400 upgrade. All
problems go away when I use the original 604 120. If I play mp3's
while the drive is connected to the adaptec/apple 2930C scsi card and
generate a system load, the sound drops out and this shows up in my
log.. 

dmasound_pmac: tx-irq: xfer died - patching it up...

The app then freezes and I have to reload the module before I can
restore sound. By slowing the card down to a 5Mhz clock I can get
around this.

I can reproduce the problem in seconds by playing an mp3 and
generating some traffic across my 530tx 10/100 nic (8139too). Same log
and same fix as before. 

I have no work around for this. Instead I use the on board mace and
deal with lower nfs performance.  

I should point out that it's not just an mp3 under xmms that dies.
Same situation with xine, mpg123 or any app that uses
the dmasound module.


Kernel 2.4.18 ( same symptoms with 2.4.10 and 2.4.19)
PowerMac 8500 
XLR8 Carrier Card w/G4 400 45Mhz bus.