From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: ata-piix.c (and libata.ko) in RHEL5.1 (build 78 currently) -
 this kernel is 2.6.18 baqsed
Date: Fri, 22 Feb 2008 17:03:12 +0000
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To: Mark Lord <liml@rtr.ca>
Cc: Alan Cox <alan@redhat.com>, "Richardson, Charlotte" <Charlotte.Richardson@stratus.com>, jgarzik@pobox.com, "Petrakis, Peter" <Peter.Petrakis@stratus.com>, "Duval, Dan" <Dan.Duval@stratus.com>, "Dailey, Nate" <Nate.Dailey@stratus.com>, linux-ide@vger.kernel.org

> 3) It is critical to ensure that the ATA "ctl" register is never
> written to when no drive is attached.  This means bracketing the SRST
> sequence to first do a PCS detection before permitting the SRST.
> If "ctl" is accessed with no drive attached, the machine locks up hard.

At least for PATA you probably need to disable IORDY handshaking before
the reset and probe.

Alan