RPXLite 823 PCMCIA troubles

[Mark S. Mathews]

Hey Dan,

On Tue, 30 Nov 1999, Dan Malek wrote:

> Mark S. Mathews wrote:

> > We've been working with the embedded 2.2.13 kernel on an RPX-Lite CW with
> > a XPC823ZT66A processor running at the 50MHz/8MHz setting.
> 
> 
> It's not only the RPX Lite.....I have a variety of 8xx boards
> and when I have trouble like this with a particular card, it
> occurs in all of the boards.

Hmmmm.  The way ours "works for awhile", I'm wondering if there's a
problem w/ the way the 8xx is handling the WAIT# when the MMU is enabled
(?)

> 
> 
> > ............ but our
> > accesses to the common memory regions of the card are twitchy.
> 
> 
> Same thing I have seen.  The I/O and attribute regions seem
> to work OK, but memory regions don't.....on more than one
> type of card.

This is good to know.  Our card supports I/O or memory access to the
shared memory.  We'll shift over to the I/O and try that.


> > .....but eventually we wind up with a machine-check.
> 
> Which points to some kind of bus timing or protocol problem.

We've been running _lots_ of experiments with the timing settings.  So far
3,10,6 seems to work best....but it still fails.


> > runs well on the x86, our PowerBook, and on a different 860 based platform
> > (non-Linux, no MMU) so we're fairly confident it isn't the code.
> 
> Well now, that's interesting (the no MMU, not the non-Linux
> part :-).  With the MMU disabled, the accesses behave as guarded.

I've seen the 'guarded' thing around in the sources, but I'm not sure what
it's all about.  Guess I should look. ;-)

> This is something I have not properly implemented on the 8xx,
> and with my somewhat sloppy use of eieio() and synchronization,
> I am always waiting for this to come back and haunt me.  Notice
> how I buried this important fact in this paragraph.  I will now
> properly implement this (yet tonight).  Tell me the kernel version
> you are using and I will send some updates for your testing.

embedded kernel 2.2.13


> How does someone (like me :-) determine what a PCMCIA interface
> in something like a PowerBook uses for bus timing?

I'm not really sure.  Have to ask David, it's probably buried in pcmcia-cs
somewhere.


> > One specific question...when setting up the PCMCIA bus timings, the 823
> > book lists the settings in units of "clock cycles".  Which clock?
> 
> It is the CLKOUT (system/bus) clock.  On the 66MHz processor,
> this better be 33 MHz (processor clock / 2).  For 50 MHz or
> less, the CLKOUT is the processor clock.

BIG help!  Thanks a million.

We'll keep trying and let you know.

-Mark

Mark S. Mathews

AbsoluteValue Software     Web:    http://www.absoval.com
P.O. Box 941149            e-mail: mark at absoval.com
Maitland, FL 32794-1149    Phone:  407.644.8582
USA                        Fax:    407.539.1294


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