Betcha all were hoping I had gone away huh?
I sent a query to o2micro about the OZ6933 cardbus bridge detailing my woes and was
informed (within
the limits of what the kind man could tell me given this info is undocumented) of a
couple of points.
Firstly the OZ6933 bridge should have a latency of 0x40.
But secondly there is an undocumented register that deals with the way the bridge
handles burst
transfers. It's pci register 0x94 and it has a couple of possible values. Mine
contains 0xe8 on
bootup, but if I poke 0xea into it a couple of things happen.
Both my cardbus ehci cards start working perfectly!!
My VIA chipset firewire card goes from 4mb/s transfer rate to >20mb/s (more !!)
I have added this to my boot scripts and the problem has dissappeared.
/bin/setpci -s 02:09.0 LATENCY_TIMER=40
/bin/setpci -s 02:09.1 LATENCY_TIMER=40
/usr/bin/X11/pcitweak -w 02:09:0 -b 0x94 0xea
I'm waiting on more info from o2 to see if it's worth me submitting a pci-quirk patch
to set these
values. I did notice someone on the alsa list was having the same problem with an
audio card that
busmastered. I'll see if I can get hold of him to try this as well.
Thanks everyone for putting up with my dumb questions and constant badgering. It's
been another bit
of a learning curve for me.
Regards,
Brad
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