From 3f7f26e990ff3a91410a89fd187aac8a4aaff824 Mon Sep 17 00:00:00 2001
From: John Baldwin <jhb@FreeBSD.org>
Date: Wed, 28 Nov 2007 22:22:05 +0000
Subject: [PATCH] MFamd64: 1.109 of pci_cfgreg.c which changes pci_cfgdisable()
 into a nop for type #1 similar to what other OS's do.

MFC after:	3 days
---
 sys/i386/pci/pci_cfgreg.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sys/i386/pci/pci_cfgreg.c b/sys/i386/pci/pci_cfgreg.c
index 9bdfe29a9da5..e8be30547ec1 100644
--- a/sys/i386/pci/pci_cfgreg.c
+++ b/sys/i386/pci/pci_cfgreg.c
@@ -280,11 +280,15 @@ pci_cfgdisable(void)
 {
 	switch (cfgmech) {
 	case CFGMECH_1:
-		outl(CONF1_ADDR_PORT, 0);
+		/*
+		 * Do nothing for the config mechanism 1 case.
+		 * Writing a 0 to the address port can apparently
+		 * confuse some bridges and cause spurious
+		 * access failures.
+		 */
 		break;
 	case CFGMECH_2:
 		outb(CONF2_ENABLE_PORT, 0);
-		outb(CONF2_FORWARD_PORT, 0);
 		break;
 	}
 }