Date: Wed, 5 Apr 1995 02:00:30 -0400 From: steve2 (Steve Gerakines) To: freebsd-hackers@FreeBSD.org Subject: Re: Colorado Jumbo 250MB ft, and FreeBSD 2.0R Message-ID: <199504050600.CAA09235@genesis.tiac.net>
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> > Also, a number of people have reported to be having problems with the
> > driver recognizing their tape drives. They sound very much like
> > timing problems. At one time the timing characteristics of the driver
> > worked for almost everyone as long as your CPU and bus speed was not
> > on the extreme in either direction. It seems with PCI and/or pentium
> > systems this may no longer be the case. Has anyone examined the DELAY
> > (microtime?) function to see if it is running noticeably faster on those
> > systems?
>
> Bruce, do we need to something with the DELAY code? I have 4 different
> Pentiums here, 3 w/PCI if you need someone to run some test code.
This turned out to be the culprit. If you look at the code around line
1473 of the driver in ftintr_wait() it is doing:
for (retries = 0; retries < 10000; retries++) {
DELAY(100);
...
}
This used to allow up to 1 second for a recalibrate or seek to
succeed before giving up but now it is a bit too fast for some systems.
Someone had suggested a while back that the count be bumped up to
100000 and I thought that was a committed fix. I thought wrong. :-(
I asked Paul Richards to bump up the retries to 20000 and increase
the delay in that loop to 200. That should give us around 3-4 seconds
and should be enough to avoid any further grief. If you're in there
mucking around anyhow Rod maybe you could do this at the same time.
- Steve
steve2@genesis.tiac.net
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