Re: Greetings. Having a FIFO overrun when my amplc_pci230 card is set on the other side of a PCI bridge

On Fri, 2006-01-27 at 15:47 +0000, Ian Abbott wrote:
> My guess is that the driver is always reading 0xFFFF from the ADCCON 
> register that has the "ADC busy" bit.  The ADCCON is in the same region 
> as the ADCDATA register, so I think the driver is reading 0xFFFF from 
> all registers in that region.  (The digital I/O, counter timer and 
> interrupt control registers are in a separate region to the ADC and DAC 
> stuff.)
> 
> It would be interesting to change the following line in amplc_pci230.c 
> to check this suspicion:
> 
> 			rt_printk("timeout\n");
> 
> becomes:
> 
> 			rt_printk("timeout (adccon=%x)\n", status);
> 
> If it prints "timeout (adccon=ffff)" then my suspicion is correct.

Cool. I'll try that out. What would it mean if is reading that?

> 
> > I'm finding trouble with other PCI cards on the expansion, so it could
> > be a chipset issue or a general linux problem. If you can make an
> > educated guess as to what's causing the timeout across the PCI bridge,
> > I'd appreciate it. Do you think interrupts are simply not being
> > propagated? Maybe I/O or memory port data isn't getting to the card?
> 
> ./inpn won't be using interrupts, but the other bug-fix for the 
> never-ending interrupts suggests that interrupts are getting through and 
> that the region containing the interrupt status and control registers is 
> at least partially working.  The region containing the ADC and DAC 
> registers probably isn't working, but I don't know if that is due to the 
> PLX PCI9052 bridge chip on the card, the PCI-to-PCI bridge or something 
> else.  The fact that you're having trouble with other cards lets us off 
> the hook a bit unless they are also using PLX chips!

All the cards I am  having trouble with are using PLX chips of different
model numbers. I did try a regular netgear ethernet card last month and
it worked in all the slots.

I've delved a bit deeper by trying a number of different configurations.
My tests have involved using a different card that has also been giving
me trouble. I have my original 4U rackmount box, which has 3 main PCI
slots and 9 expansion slots hanging off a Pericom PCI bridge (intel
21152 compatible). I've also got an entire expansion chassis which holds
12 cards off of 4 intel 21152 bridges. It connects to a host pc via a
PCI expansion card. Now, I've also gotten ahold of a regular desktop PC
and was able to test the card (in this case a sealevel 8009 digital I/O
card). Bascially, if the card is hanging off of either of the two
bridges attached to the 4U rackmount, it fails. If it's on the 4U
rackmount's main PCI bus, or attached to the desktop's pci bus, or
attached to the desktop PC via the external chassis's bridge, it works
just fine. So I'm guessing there's a problem with the main motherboard
in the 4U rackmount's chipset or BIOS. 

We've got a support call in to the vendor, so hopefully we'll get that
resolved soon.


> > Either way, thanks for looking in to this.
> 
> No problem.  It would be nice to get to the bottom of this.



> 
> -- 
> -=( Ian Abbott _at_ MEV Ltd.    E-mail: <abbotti_at_mev.co.uk>        )=-
> -=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-
> 
-- 
Michael R. Head <burner_at_suppressingfire.org>
GPG: http://www.suppressingfire.org/~burner/gpg.key.txt [0x4C9DA1D0]