[PATCH] PCI: remove unconditional PCI ACPI IRQ routing

From: Bjorn Helgaas <bjorn.helgaas@hp.com>

Now that PCI interrupts are routed in pci_enable_device(), remove the
unconditional routing previously done in pci_acpi_init().

This has the potential to break drivers that don't use pci_enable_device()
correctly, so I also added a "pci=routeirq" kernel option that restores the
previous behavior.  I intend to remove that option, along with all the code
below, in a month or so.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

Documentation/kernel-parameters.txt

@@ -912,6 +912,10 @@ running once the system is up.
 					enabled.
 		noacpi			[IA-32] Do not use ACPI for IRQ routing
 					or for PCI scanning.
+		routeirq		Do IRQ routing for all PCI devices.
+					This is normally done in pci_enable_device(),
+					so this option is a temporary workaround
+					for broken drivers that don't call it.
 
 		firmware		[ARM] Do not re-enumerate the bus but
 					instead just use the configuration

arch/i386/pci/acpi.c

@@ -15,6 +15,7 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_device *device, int do
 	return pcibios_scan_root(busnum);
 }
 
+extern int pci_routeirq;
 static int __init pci_acpi_init(void)
 {
 	struct pci_dev *dev = NULL;
@@ -30,14 +31,27 @@ static int __init pci_acpi_init(void)
 	pcibios_scanned++;
 	pcibios_enable_irq = acpi_pci_irq_enable;
 
-	/*
-	 * PCI IRQ routing is set up by pci_enable_device(), but we
-	 * also do it here in case there are still broken drivers that
-	 * don't use pci_enable_device().
-	 */
-	while ((dev = pci_find_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL)
-		acpi_pci_irq_enable(dev);
-
+	if (pci_routeirq) {
+		/*
+		 * PCI IRQ routing is set up by pci_enable_device(), but we
+		 * also do it here in case there are still broken drivers that
+		 * don't use pci_enable_device().
+		 */
+		printk(KERN_INFO "** Routing PCI interrupts for all devices because \"pci=routeirq\"\n");
+		printk(KERN_INFO "** was specified.  If this was required to make a driver work,\n");
+		printk(KERN_INFO "** please email the output of \"lspci\" to bjorn.helgaas@hp.com\n");
+		printk(KERN_INFO "** so I can fix the driver.\n");
+		while ((dev = pci_find_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL)
+			acpi_pci_irq_enable(dev);
+	} else {
+		printk(KERN_INFO "** PCI interrupts are no longer routed automatically.  If this\n");
+		printk(KERN_INFO "** causes a device to stop working, it is probably because the\n");
+		printk(KERN_INFO "** driver failed to call pci_enable_device().  As a temporary\n");
+		printk(KERN_INFO "** workaround, the \"pci=routeirq\" argument restores the old\n");
+		printk(KERN_INFO "** behavior.  If this argument makes the device work again,\n");
+		printk(KERN_INFO "** please email the output of \"lspci\" to bjorn.helgaas@hp.com\n");
+		printk(KERN_INFO "** so I can fix the driver.\n");
+	}
 #ifdef CONFIG_X86_IO_APIC
 	if (acpi_ioapic)
 		print_IO_APIC();

arch/i386/pci/common.c

@@ -23,6 +23,7 @@ extern  void pcibios_sort(void);
 unsigned int pci_probe = PCI_PROBE_BIOS | PCI_PROBE_CONF1 | PCI_PROBE_CONF2 |
 				PCI_PROBE_MMCONF;
 
+int pci_routeirq;
 int pcibios_last_bus = -1;
 struct pci_bus *pci_root_bus = NULL;
 struct pci_raw_ops *raw_pci_ops;
@@ -227,6 +228,9 @@ char * __devinit  pcibios_setup(char *str)
 	} else if (!strcmp(str, "assign-busses")) {
 		pci_probe |= PCI_ASSIGN_ALL_BUSSES;
 		return NULL;
+	} else if (!strcmp(str, "routeirq")) {
+		pci_routeirq = 1;
+		return NULL;
 	}
 	return str;
 }

arch/ia64/pci/pci.c

@@ -46,6 +46,8 @@
 #define DBG(x...)
 #endif
 
+static int pci_routeirq;
+
 /*
  * Low-level SAL-based PCI configuration access functions. Note that SAL
  * calls are already serialized (via sal_lock), so we don't need another
@@ -141,13 +143,28 @@ extern acpi_status acpi_map_iosapic (acpi_handle, u32, void*, void**);
 
 	acpi_get_devices(NULL, acpi_map_iosapic, NULL, NULL);
 #endif
-	/*
-	 * PCI IRQ routing is set up by pci_enable_device(), but we
-	 * also do it here in case there are still broken drivers that
-	 * don't use pci_enable_device().
-	 */
-	while ((dev = pci_find_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL)
-		acpi_pci_irq_enable(dev);
+
+	if (pci_routeirq) {
+		/*
+		 * PCI IRQ routing is set up by pci_enable_device(), but we
+		 * also do it here in case there are still broken drivers that
+		 * don't use pci_enable_device().
+		 */
+		printk(KERN_INFO "** Routing PCI interrupts for all devices because \"pci=routeirq\"\n");
+		printk(KERN_INFO "** was specified.  If this was required to make a driver work,\n");
+		printk(KERN_INFO "** please email the output of \"lspci\" to bjorn.helgaas@hp.com\n");
+		printk(KERN_INFO "** so I can fix the driver.\n");
+		while ((dev = pci_find_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL)
+			acpi_pci_irq_enable(dev);
+	} else {
+		printk(KERN_INFO "** PCI interrupts are no longer routed automatically.  If this\n");
+		printk(KERN_INFO "** causes a device to stop working, it is probably because the\n");
+		printk(KERN_INFO "** driver failed to call pci_enable_device().  As a temporary\n");
+		printk(KERN_INFO "** workaround, the \"pci=routeirq\" argument restores the old\n");
+		printk(KERN_INFO "** behavior.  If this argument makes the device work again,\n");
+		printk(KERN_INFO "** please email the output of \"lspci\" to bjorn.helgaas@hp.com\n");
+		printk(KERN_INFO "** so I can fix the driver.\n");
+	}
 
 	return 0;
 }
@@ -443,6 +460,8 @@ pcibios_align_resource (void *data, struct resource *res,
 char * __init
 pcibios_setup (char *str)
 {
+	if (!strcmp(str, "routeirq"))
+		pci_routeirq = 1;
 	return NULL;
 }