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Date:      Fri, 17 Nov 2000 16:45:11 -0700 (MST)
From:      Nate Williams <nate@yogotech.com>
To:        Warner Losh <imp@village.org>
Cc:        Steve Price <sprice@hiwaay.net>, Mark.Andrews@nominum.com, stable@FreeBSD.ORG
Subject:   Re: 4.2-BETA hangs on boot 
Message-ID:  <14869.49927.736257.730814@nomad.yogotech.com>
In-Reply-To: <200011172237.PAA77876@harmony.village.org>
References:  <20001117162836.N62344@bonsai.knology.net> <20001116204344.B62344@bonsai.knology.net> <20001116195957.A62344@bonsai.knology.net> <200011170209.eAH297q51130@drugs.dv.isc.org> <200011172203.PAA77619@harmony.village.org> <200011172237.PAA77876@harmony.village.org>

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[ PCIC defaults to polling mode ]

> There are six million brands of laptop in the world.  To be honest,
> this thread is basically the first one to say that there's something
> wrong.  PAO3 has done this for some time, if I understand thigns
> correctly, and hasn't reported problems.

FWIW, I switched *from* polling mode to IRQ mode in FreeBSD 2.2.X (can't
remember) for two reasons:

1) suspend/resume works *much* more reliably.  (However, I ended up
   rewriting the suspend/resume code anyway).
2) Too many folks complained that polling didn't work reliably.

However, I believe the second was related to the fact that there were
races in the polling code (which came from PAO), such that polling was
*always* being done, regardless of whether or not the IRQ was being
used.

Finally, stating the 'PAO' has done it for some time is not (IMO) a
great argument.  In the past, PAO has done lots of things incorrectly,
and that things worked at all was merely good luck.

Polling 'should' work in all cases, although suspend/resume may not work
reliably (races and such).  If it doesn't work on Steve's laptop,
something is messed up with the PCIC probing/setup, since it should work
fine.

The biggest advantage for supporting 'polling by default' is the fact
that IRQ's are a precious commodity on newer hardware, and 'wasting' one
just for insertion/removal events seems a waste.

(Steve, on a whim, is PnP turned *OFF* in your BIOS?)



Nate


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