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Date: Wed, 17 Oct 2001 20:21:11 -0700
From: Tim Hockin <thockin@sun.com>
Organization: Sun Microsystems, Inc.
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To: Andre Hedrick <andre@linuxdiskcert.org>
CC: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        andre@linux-ide.org
Subject: Re: [PATCH] IDE initialization fix
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Andre Hedrick wrote:

> > for chipsets does not get called.  I'll speak specifically about the CSB5.
> > The CSB5 in non-native mode has a PCI irqline register forced to 0.  The
> > PCI probe then skips it's PCI init and it never gets called.


OK!  This is what I have learned.  The ide-pci init code has one case that
isn't caught.  Perhaps you can clarify what it means, for me.

* If an IDE controller has a PCI IRQ and has class code bit 0x5 set, it is
100% native.

* CSB5 _CAN_NOT_ have a PCI IRQ assigned (RO register).

* CSB5 spec clearly indicates that you can turn on class code bits 0x5 for
native mode operation.

* My system has the native mode bits turned on, but not an IRQ.  The driver
incorrectly drops this case into teh "bad irq" case.

* Solution: cleanup probe to something like:

if ((is_storage_ide || is_storage_other) && native_bits && pciirq) {
        /* 100% native mode */
        init_chipset();
} else if ((is_storage_ide || is_storage_other) && native_bits) {
        /* native mode */
        init_chipset();
} else if (is_storage_ide || is_storage_other) {
        /* non-native mode */
        init_chipset();
} else {
        /* what here ?!?! */
}

or simpler:

if (is_storage_ide || is_storage_other) {
	if (native_bits && pciirq) {
		/* 100% native mode */
	} else if (native_bits) {
		/* plain-old native mode */
	} else {
		/* non-native mode */
	}
	init_chipset();
} else {
	/* what here?!? */
}


What do you think of this case?  The other alternative is to turn OFF
native bits on any CSB5, since it can't have a PCI IRQ assigned.

Please let me know, and I'll work up and test a patch.

-- 
Tim Hockin
Systems Software Engineer
Sun Microsystems, Cobalt Server Appliances
thockin@sun.com
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