[PATCH] pci=usepirqmask option.

Last week I sent you a patch adding a config option to honor the pirq mask
in the PCI routing table.  On your suggestion, Cory Bell made it a command
line option using the pci= interface and we both agree with you, it's
-much- cleaner this way.

Patch against 2.5.6 (Cory's submitting for 2.4, I've tested and submitting
towards 2.5).  All credit goes to Cory Bell, with only minor input and
testing from myself.

Documentation/kernel-parameters.txt

@@ -467,6 +467,14 @@ running once the system is up.
 					whatever the firmware may have
 					done.
 
+		usepirqmask		[IA-32] Honor the possible IRQ mask
+					stored in the BIOS $PIR table. This is
+					needed on some systems with broken
+					BIOSes, notably some HP Pavilion N5400
+					and Omnibook XE3 notebooks. This will
+					have no effect if ACPI IRQ routing is
+					enabled.
+
 	pd.		[PARIDE]
 
 	pf.		[PARIDE]

arch/i386/kernel/pci-i386.h

@@ -18,6 +18,7 @@
 #define PCI_NO_SORT		0x0100
 #define PCI_BIOS_SORT		0x0200
 #define PCI_NO_CHECKS		0x0400
+#define PCI_USE_PIRQ_MASK	0x0800
 #define PCI_ASSIGN_ROMS		0x1000
 #define PCI_BIOS_IRQ_SCAN	0x2000
 #define PCI_ASSIGN_ALL_BUSSES	0x4000

arch/i386/kernel/pci-irq.c

@@ -570,6 +570,10 @@ static int pcibios_lookup_irq(struct pci_dev *dev, int assign)
 	 * reported by the device if possible.
 	 */
 	newirq = dev->irq;
+	if (!((1 << newirq) & mask)) {
+		if ( pci_probe & PCI_USE_PIRQ_MASK) newirq = 0;
+		else printk(KERN_WARNING "PCI: IRQ %i for device %s doesn't match PIRQ mask - try pci=usepirqmask\n", newirq, dev->slot_name);
+	}
 	if (!newirq && assign) {
 		for (i = 0; i < 16; i++) {
 			if (!(mask & (1 << i)))
@@ -588,7 +592,8 @@ static int pcibios_lookup_irq(struct pci_dev *dev, int assign)
 		irq = pirq & 0xf;
 		DBG(" -> hardcoded IRQ %d\n", irq);
 		msg = "Hardcoded";
-	} else if (r->get && (irq = r->get(pirq_router_dev, dev, pirq))) {
+	} else if ( r->get && (irq = r->get(pirq_router_dev, dev, pirq)) && \
+	((!(pci_probe & PCI_USE_PIRQ_MASK)) || ((1 << irq) & mask)) ) {
 		DBG(" -> got IRQ %d\n", irq);
 		msg = "Found";
 	} else if (newirq && r->set && (dev->class >> 8) != PCI_CLASS_DISPLAY_VGA) {
@@ -622,7 +627,9 @@ static int pcibios_lookup_irq(struct pci_dev *dev, int assign)
 			continue;
 		if (info->irq[pin].link == pirq) {
 			/* We refuse to override the dev->irq information. Give a warning! */
-		    	if (dev2->irq && dev2->irq != irq) {
+		    	if ( dev2->irq && dev2->irq != irq && \
+			(!(pci_probe & PCI_USE_PIRQ_MASK) || \
+			((1 << dev2->irq) & mask)) ) {
 		    		printk(KERN_INFO "IRQ routing conflict for %s, have irq %d, want irq %d\n",
 				       dev2->slot_name, dev2->irq, irq);
 		    		continue;

arch/i386/kernel/pci-pc.c

@@ -1343,6 +1343,9 @@ char * __devinit  pcibios_setup(char *str)
 	} else if (!strcmp(str, "assign-busses")) {
 		pci_probe |= PCI_ASSIGN_ALL_BUSSES;
 		return NULL;
+	} else if (!strcmp(str, "usepirqmask")) {
+		pci_probe |= PCI_USE_PIRQ_MASK;
+		return NULL;
 	} else if (!strncmp(str, "irqmask=", 8)) {
 		pcibios_irq_mask = simple_strtol(str+8, NULL, 0);
 		return NULL;