Date: Wed, 3 Dec 1997 08:39:55 +0100 (MET) From: Søren Schmidt <sos@FreeBSD.dk> To: deischen@iworks.interworks.org (Daniel M. Eischen) Cc: sos@FreeBSD.dk, freebsd-hackers@FreeBSD.ORG, freebsd-mobile@FreeBSD.ORG Subject: Re: Fix for slow reacting ATAPI CD-ROM Message-ID: <199712030739.IAA01569@sos.freebsd.dk> In-Reply-To: <199712030408.WAA11699@iworks.InterWorks.org> from "Daniel M. Eischen" at "Dec 2, 97 10:08:48 pm"
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In reply to Daniel M. Eischen who wrote:
>
> I was able to lower the wait time to 75 usec for my CD-ROM drive,
> but anything <= 70 usecs would not work.
>
> According to the comments in atapi.h:
>
> #define AT_DRQT_MPROC 0 /* microprocessor DRQ - 3 msec delay */
> #define AT_DRQT_INTR 1 /* interrupt DRQ - 10 msec delay */
> #define AT_DRQT_ACCEL 2 /* accelerated DRQ - 50 usec delay */
>
> my CD-ROM drive should have a 50usec delay. The code in atapi.c
> uses these numbers without any tolerance. I assume these numbers
> come from some sort of ATAPI spec, but shouldn't we allow some
> tolerance? Increasing these waits will not affect drives that
> conform to the times, so I don't see why they can't be larger.
Hmm, I *think* the above values are directly from the spec, but
havn't checked. I'll go check when I get home, and changing it to
100usec really shouldn't be a problem, and should provide you
with a safe margin...
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Søren Schmidt (sos@FreeBSD.org) FreeBSD Core Team
Even more code to hack -- will it ever end
..
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