From 265ed03ff5fd35becbd3a0e5b8e09ee315236a04 Mon Sep 17 00:00:00 2001
From: Nate Lawson <njl@FreeBSD.org>
Date: Sat, 12 Jan 2008 22:13:12 +0000
Subject: [PATCH] Fix GPE livelock that occurs on HP/Compaq laptops, mostly in
 the thermal zone code.  The GPE handler method (i.e. _L00) generates various
 Notify events that need to be run to completion before the GPE is re-enabled.
 In ACPI-CA, we queue an asynch callback at the same priority as a Notify so
 that it will only run after all Notify handlers have completed.  The callback
 re-enables the GPE afterwards.  We also changed the priority of Notifies to
 be the same as GPEs, given the possibility that another GPE could arrive
 before the Notifies have completed and we don't want it to get queued ahead
 of the rest.

The ACPI-CA change was submitted by Alexey Starikovskiy (SUSE) and will
appear in a later release.  Special thanks to him for helping track this
bug down.

MFC after:	1 week
Tested by:	jhb, Yousif Hassan <yousif / alumni.jmu.edu>
---
 sys/contrib/dev/acpica/evgpe.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/sys/contrib/dev/acpica/evgpe.c b/sys/contrib/dev/acpica/evgpe.c
index e470eaeff97..d18a1d7dd96 100644
--- a/sys/contrib/dev/acpica/evgpe.c
+++ b/sys/contrib/dev/acpica/evgpe.c
@@ -123,6 +123,10 @@
 
 /* Local prototypes */
 
+static void
+AcpiEvAsynchEnableGpe (
+    void                    *Context);
+
 static void ACPI_SYSTEM_XFACE
 AcpiEvAsynchExecuteGpeMethod (
     void                    *Context);
@@ -684,14 +688,26 @@ AcpiEvAsynchExecuteGpeMethod (
         }
     }
 
-    if ((LocalGpeEventInfo.Flags & ACPI_GPE_XRUPT_TYPE_MASK) ==
+    /* Defer enabling of GPE until all notify handlers are done */
+    AcpiOsExecute(OSL_NOTIFY_HANDLER, AcpiEvAsynchEnableGpe, GpeEventInfo);
+    return_VOID;
+}
+
+static void
+AcpiEvAsynchEnableGpe (
+    void                    *Context)
+{
+    ACPI_GPE_EVENT_INFO     *GpeEventInfo = (void *) Context;
+    ACPI_STATUS             Status;
+
+    if ((GpeEventInfo->Flags & ACPI_GPE_XRUPT_TYPE_MASK) ==
             ACPI_GPE_LEVEL_TRIGGERED)
     {
         /*
          * GPE is level-triggered, we clear the GPE status bit after
          * handling the event.
          */
-        Status = AcpiHwClearGpe (&LocalGpeEventInfo);
+        Status = AcpiHwClearGpe (GpeEventInfo);
         if (ACPI_FAILURE (Status))
         {
             return_VOID;
@@ -700,7 +716,7 @@ AcpiEvAsynchExecuteGpeMethod (
 
     /* Enable this GPE */
 
-    (void) AcpiHwWriteGpeEnableReg (&LocalGpeEventInfo);
+    (void) AcpiHwWriteGpeEnableReg (GpeEventInfo);
     return_VOID;
 }