[PATCH] PCI: Provide a boot parameter to disable MSI

Several drivers are starting to grow options to disable MSI.  However,
it's often a host chipset issue, not something which individual drivers
should handle.  So we add the pci=nomsi kernel parameter to allow the user
to disable MSI modes for systems we haven't added to the quirk list yet.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index aea8b258b9b8..a77e79c8c82e 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -765,8 +765,11 @@ void pci_disable_msi(struct pci_dev* dev)
         u16 control;
         unsigned long flags;
 
+        if (!pci_msi_enable)
+                return;
         if (!dev)
                 return;
+
         pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
         if (!pos)
                 return;
@@ -1026,6 +1029,8 @@ void pci_disable_msix(struct pci_dev* dev)
         int pos, temp;
         u16 control;
 
+        if (!pci_msi_enable)
+                return;
         if (!dev)
                 return;
 
@@ -1152,6 +1157,11 @@ void msi_remove_pci_irq_vectors(struct pci_dev* dev)
         }
 }
 
+void pci_no_msi(void)
+{
+        pci_msi_enable = 0;
+}
+
 EXPORT_SYMBOL(pci_enable_msi);
 EXPORT_SYMBOL(pci_disable_msi);
 EXPORT_SYMBOL(pci_enable_msix);