pci, acpi: reroute PCI interrupt to legacy boot interrupt equivalent

Some chipsets (e.g. intel 6700PXH) generate a legacy INTx when the
IRQ entry in the chipset's IO-APIC is masked (as, e.g. the RT kernel
does during interrupt handling). On chipsets where this INTx generation
cannot be disabled, we reroute the valid interrupts to their legacy
equivalent to get rid of spurious interrupts that might otherwise bring
down (vital) interrupt lines through spurious interrupt detection in
note_interrupt().

This patch benefited from discussions with Alexander Graf, Torsten Duwe,
Ihno Krumreich, Daniel Gollub, Hannes Reinecke. The conclusions we drew
and the patch itself are the authors' responsibility alone.

Signed-off-by: Stefan Assmann <sassmann@suse.de>
Signed-off-by: Olaf Dabrunz <od@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/pci.h b/include/linux/pci.h
index d18b1dd49fab..6755cf5ac109 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -117,6 +117,11 @@ enum pci_dev_flags {
         PCI_DEV_FLAGS_MSI_INTX_DISABLE_BUG = (__force pci_dev_flags_t) 1,
 };
 
+enum pci_irq_reroute_variant {
+        INTEL_IRQ_REROUTE_VARIANT = 1,
+        MAX_IRQ_REROUTE_VARIANTS = 3
+};
+
 typedef unsigned short __bitwise pci_bus_flags_t;
 enum pci_bus_flags {
         PCI_BUS_FLAGS_NO_MSI   = (__force pci_bus_flags_t) 1,
@@ -194,6 +199,7 @@ struct pci_dev {
         unsigned int    no_d1d2:1;   /* only allow d0 or d3 */
         unsigned int    block_ucfg_access:1;    /* userspace config space access is blocked */
         unsigned int    broken_parity_status:1; /* Device generates false positive parity */
+        unsigned int    irq_reroute_variant:2;  /* device needs IRQ rerouting variant */
         unsigned int    msi_enabled:1;
         unsigned int    msix_enabled:1;
         unsigned int    is_managed:1;