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authorChristoph Hellwig <hch@lst.de>2016-07-12 18:20:18 +0900
committerBjorn Helgaas <bhelgaas@google.com>2016-07-21 15:57:03 -0500
commit4ef33685aa0957d771e068b60a5f3ca6b47ade1c (patch)
tree34e9fee3bd177657e18f56a4d5d0701f6f3c20f5 /Documentation/PCI/MSI-HOWTO.txt
parentaff171641d181ea573380efc3f559c9de4741fc5 (diff)
PCI: Spread interrupt vectors in pci_alloc_irq_vectors()
Set the affinity_mask in the PCI device before allocating vectors so that the affinity can be propagated through the MSI descriptor structures to the core IRQ code. To facilitate this, new __pci_enable_msi_range() and __pci_enable_msix_range() helpers are factored out of their not prefixed variants which assigning the new IRQ affinity mask in the PCI device so that the low-level interrupt code can perform the interrupt affinity assignment and do node-local allocations. A new PCI_IRQ_NOAFFINITY flag is added to pci_alloc_irq_vectors() so that this function can also be used by drivers that don't wish to use the automatic affinity assignment. [bhelgaas: omit "else" after "return" consistently] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Alexander Gordeev <agordeev@redhat.com>
Diffstat (limited to 'Documentation/PCI/MSI-HOWTO.txt')
-rw-r--r--Documentation/PCI/MSI-HOWTO.txt4
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index 0ac612b8c3fb..c55df2911136 100644
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -99,6 +99,10 @@ PCI_IRQ_NOMSI and PCI_IRQ_NOMSIX flag in case a device claims to support
MSI or MSI-X, but the support is broken, or to pass PCI_IRQ_NOLEGACY in
case the device does not support legacy interrupt lines.
+By default this function will spread the interrupts around the available
+CPUs, but this feature can be disabled by passing the PCI_IRQ_NOAFFINITY
+flag.
+
To get the Linux IRQ numbers passed to request_irq() and free_irq() and the
vectors, use the following function: