This addresses interrupt storms that were noticed after enabling MSI
in drm. I think this is due to a loose interpretation of the PCI 2.3
spec, which states that a function using MSI is prohibitted from using
INTx. It appears that some vendors interpretted that to mean that they
should handle it in hardware, while others felt it was the drivers
responsibility.
This fix will also likely resolve interrupt storm related issues with
devices other than drm.
Reviewed by: jhb@
MFC after: 3 days
dac11360f1