From alsa-devel-owner@alsa.jcu.cz  Mon Nov  9 11:25:21 1998
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	Mon, 9 Nov 1998 11:24:38 +0100
Date: Mon, 9 Nov 1998 11:24:38 +0100 (CET)
From: Jaroslav Kysela <perex@jcu.cz>
To: Paul Winkler <zarmzarm@erols.com>
cc: alsa-user@alsa.jcu.cz, alsa-devel@alsa.jcu.cz
Subject: Re: Lockups: Yes, it's the mainboard!
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On Mon, 9 Nov 1998, Paul Winkler wrote:

> A while ago, we were discussing system lockups caused by full-duplex
> recording, and the possibility that this might be caused by a problem
> with the motherboard rather than with software.
> 
> I've just upgraded my version of OSS/Linux to 3.91h and the problem
> seems to have completely gone away! (At least so far.)
> 
> According to 4front's tech support:
> > Some PC chipsets such as VIA and Intel VX have somehow broken ISA DMA.
> > We have made a simple fix to the next version which is reported
> > to work with the VIA chipset [ and may work with the VX] ...
> > This kind of problems are usually some kind of timing problems. Some
> > chipsets just lock if certain operations are performed too quickly
> > after each other.
> 
> Well, the fix seems to have worked on my system, which is based on Intel
> VX.
> 
> I hope this information will be useful to ALSA developers! I wish I knew
> more about the details of the problem...

This is good and bad news... I don't have access to broken motherboard to
fix this problem and we probably willn't see source for OSS commercial.
Maybe you or some other with broken motherboard can play a little bit
with code in alsa-driver/kernel/isadma.c and add some delays (snd_delay(1)
or something other) between lines in this file. I still hope, that
problems are related to ISA DMA (thus PCI -> ISA bridges).

								Jaroslav

-----
Jaroslav Kysela <perex@jcu.cz>
Academic Computer Centre, University of South Bohemia
Branisovska 31, C. Budejovice, CZ-370 05 Czech Republic


