From owner-freebsd-current  Wed Sep 30 14:30:35 1998
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From: Kevin Day <toasty@home.dragondata.com>
Message-Id: <199809302129.QAA18323@home.dragondata.com>
Subject: Re: Long IDE probes?
In-Reply-To: <19980930130459.A4393@Denninger.Net> from Karl Denninger at "Sep 30, 98 01:04:59 pm"
To: karl@Denninger.Net (Karl Denninger)
Date: Wed, 30 Sep 1998 16:29:39 -0500 (CDT)
Cc: tom@uniserve.com, dnelson@emsphone.com, bright@hotjobs.com,
        current@FreeBSD.ORG
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> > > Are the delay lengths reasonable?  I don't know.  Aren't there specs on
> > > this stuff from the IDE and SCSI camps?
> > 
> >   The IDE delays just don't exist if you don't bother probing for devices
> > that aren't there.
> 
> The IDE delays are far, far too long, unless someone can convince me that
> *after booting* a device would require *another* 30 seconds to come ready
> (remember, we're talking after power-on, not from the time the kernel is
> done loading).

To shed some light.... This is all according to the ATA specs:

We throw a hardware reset.

The device must set the BSY flag within 400ns, after RESET- is turned off.
If we can see BSY, the device is there.  We should be able to stop at this
point, as suposedly this is a yes/no test for a device being present.

However, after this, we're supposed to do some magic, then the device has 31
seconds to respond. 

Possibly there are some rogue devices/chipsets out there that fool the
driver with the BSY test, and so we're forced to wait for the full 31
seconds for the reply?

Not sure, but that's what the 'standard' is.

Kevin

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