--- /dev/null
+From 1ea76fbadd667b19c4fa4466f3a3b55a505e83d9 Mon Sep 17 00:00:00 2001
+From: Jiang Liu <jiang.liu@linux.intel.com>
+Date: Mon, 16 Feb 2015 10:11:13 +0800
+Subject: x86/irq: Fix regression caused by commit b568b8601f05
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Jiang Liu <jiang.liu@linux.intel.com>
+
+commit 1ea76fbadd667b19c4fa4466f3a3b55a505e83d9 upstream.
+
+Commit b568b8601f05 ("Treat SCI interrupt as normal GSI interrupt")
+accidently removes support of legacy PIC interrupt when fixing a
+regression for Xen, which causes a nasty regression on HP/Compaq
+nc6000 where we fail to register the ACPI interrupt, and thus
+lose eg. thermal notifications leading a potentially overheated
+machine.
+
+So reintroduce support of legacy PIC based ACPI SCI interrupt.
+
+Reported-by: Ville Syrjälä <syrjala@sci.fi>
+Tested-by: Ville Syrjälä <syrjala@sci.fi>
+Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Acked-by: Pavel Machek <pavel@ucw.cz>
+Cc: H. Peter Anvin <hpa@zytor.com>
+Cc: Len Brown <len.brown@intel.com>
+Cc: Linus Torvalds <torvalds@linux-foundation.org>
+Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
+Cc: Sander Eikelenboom <linux@eikelenboom.it>
+Cc: linux-pm@vger.kernel.org
+Link: http://lkml.kernel.org/r/1424052673-22974-1-git-send-email-jiang.liu@linux.intel.com
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/x86/kernel/acpi/boot.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+--- a/arch/x86/kernel/acpi/boot.c
++++ b/arch/x86/kernel/acpi/boot.c
+@@ -606,6 +606,11 @@ int acpi_gsi_to_irq(u32 gsi, unsigned in
+ {
+ int rc, irq, trigger, polarity;
+
++ if (acpi_irq_model == ACPI_IRQ_MODEL_PIC) {
++ *irqp = gsi;
++ return 0;
++ }
++
+ rc = acpi_get_override_irq(gsi, &trigger, &polarity);
+ if (rc == 0) {
+ trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;