From: "Mark Chambers" <markc@mail•com>
To: "linux-ppc-embedded" <linuxppc-embedded@ozlabs•org>
Subject: Re: [RFC] handle access to non-present IO ports on 8xx
Date: Fri, 3 Jun 2005 08:08:13 -0400 [thread overview]
Message-ID: <002901c56834$ef358f60$0301a8c0@chuck2> (raw)
In-Reply-To: 1117750262.31082.73.camel@gaston
> > >
> > > Hrm... removing a PCMCIA card triggers mchecks ? that is bad... With
> > > "proper" PCMCIA controllers, those are swallowed properly when the
card
> > > is removed. The eating of the machine check is a bit too hackish to my
> > > taste... Better is to "not do that" by making sure the legacy crap
isn't
> > > trying to tap unexisting ports, but then, if PCMCIA is also a
> > > problem...
> >
> > Well, cardmgr calls the driver's shutdown/close routine as soon as
> > the card is removed. Some of those methods write to IO registers in
> > the process (eg net/pcmcia/pcnet_cs.c).
> >
> > I dont see any elegant change that could be done in PCMCIA.
>
> I know, the thing is, on platforms with a "classical" PCI<->PCMCIA
> bridge, the bridge will not issue machine checks when the card is
> removed. I don't know if that is possible with your HW setup, I suppose
> you are hooking PCMCIA directly to the CPU IO bus ...
>
I forget if I pointed this out already or not, but there's a good chance the
mchecks you are seeing are from a bad PCMCIA implementation, not
the 8xx itself. PCMCIA uses WAIT, which is a negative ACK really,
and that must be pulled up externally, so if you remove the card any
active WAIT goes away. I'd be glad to take a look at the schematics
if available and tell you if I think there might be a problem there.
Then again, maybe it doesn't matter where the mchecks are coming
from, you just need to handle them...
Mark Chambers
next prev parent reply other threads:[~2005-06-03 12:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-01 16:50 [RFC] handle access to non-present IO ports on 8xx Marcelo Tosatti
2005-06-02 2:46 ` Benjamin Herrenschmidt
2005-06-02 7:04 ` Pantelis Antoniou
2005-06-02 17:02 ` Marcelo Tosatti
2005-06-02 22:11 ` Benjamin Herrenschmidt
2005-06-03 12:08 ` Mark Chambers [this message]
2005-06-08 9:01 ` Marcelo Tosatti
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