Adjust the code to probe for the PCI config mechanism to use.

- On amd64, just assume type #1 is always used.  PCI 2.0 mandated
  deprecated type #2 and required type #1 for all future bridges which
  was well before amd64 existed.
- For i386, ignore whatever value was in 0xcf8 before testing for type #1
  and instead rely on the other tests to determine if type #1 works.  Some
  newer machines leave garbage in 0xcf8 during boot and as a result the
  kernel doesn't find PCI at all (which greatly confuses ACPI which expects
  PCI to exist when PCI busses are in the namespace).

MFC after:	3 days
Discussed with:	scottl

1 files changed, 25 insertions, 25 deletions

diff --git a/sys/i386/pci/pci_cfgreg.c b/sys/i386/pci/pci_cfgreg.c
index a6c80ae..9bdfe29 100644
--- a/sys/i386/pci/pci_cfgreg.c
+++ b/sys/i386/pci/pci_cfgreg.c
@@ -403,6 +403,7 @@ pcireg_cfgopen(void)
 	uint32_t mode1res, oldval1;
 	uint8_t mode2res, oldval2;
 
+	/* Check for type #1 first. */
 	oldval1 = inl(CONF1_ADDR_PORT);
 
 	if (bootverbose) {
@@ -410,39 +411,37 @@ pcireg_cfgopen(void)
 		    oldval1);
 	}
 
-	if ((oldval1 & CONF1_ENABLE_MSK) == 0) {
-
-		cfgmech = CFGMECH_1;
-		devmax = 32;
+	cfgmech = CFGMECH_1;
+	devmax = 32;
 
-		outl(CONF1_ADDR_PORT, CONF1_ENABLE_CHK);
-		DELAY(1);
-		mode1res = inl(CONF1_ADDR_PORT);
-		outl(CONF1_ADDR_PORT, oldval1);
+	outl(CONF1_ADDR_PORT, CONF1_ENABLE_CHK);
+	DELAY(1);
+	mode1res = inl(CONF1_ADDR_PORT);
+	outl(CONF1_ADDR_PORT, oldval1);
 
-		if (bootverbose)
-			printf("pci_open(1a):\tmode1res=0x%08x (0x%08lx)\n", 
-			    mode1res, CONF1_ENABLE_CHK);
+	if (bootverbose)
+		printf("pci_open(1a):\tmode1res=0x%08x (0x%08lx)\n",  mode1res,
+		    CONF1_ENABLE_CHK);
 
-		if (mode1res) {
-			if (pci_cfgcheck(32)) 
-				return (cfgmech);
-		}
+	if (mode1res) {
+		if (pci_cfgcheck(32)) 
+			return (cfgmech);
+	}
 
-		outl(CONF1_ADDR_PORT, CONF1_ENABLE_CHK1);
-		mode1res = inl(CONF1_ADDR_PORT);
-		outl(CONF1_ADDR_PORT, oldval1);
+	outl(CONF1_ADDR_PORT, CONF1_ENABLE_CHK1);
+	mode1res = inl(CONF1_ADDR_PORT);
+	outl(CONF1_ADDR_PORT, oldval1);
 
-		if (bootverbose)
-			printf("pci_open(1b):\tmode1res=0x%08x (0x%08lx)\n", 
-			    mode1res, CONF1_ENABLE_CHK1);
+	if (bootverbose)
+		printf("pci_open(1b):\tmode1res=0x%08x (0x%08lx)\n",  mode1res,
+		    CONF1_ENABLE_CHK1);
 
-		if ((mode1res & CONF1_ENABLE_MSK1) == CONF1_ENABLE_RES1) {
-			if (pci_cfgcheck(32)) 
-				return (cfgmech);
-		}
+	if ((mode1res & CONF1_ENABLE_MSK1) == CONF1_ENABLE_RES1) {
+		if (pci_cfgcheck(32)) 
+			return (cfgmech);
 	}
 
+	/* Type #1 didn't work, so try type #2. */
 	oldval2 = inb(CONF2_ENABLE_PORT);
 
 	if (bootverbose) {
@@ -472,6 +471,7 @@ pcireg_cfgopen(void)
 		}
 	}
 
+	/* Nothing worked, so punt. */
 	cfgmech = CFGMECH_NONE;
 	devmax = 0;
 	return (cfgmech);