From: Neil Horman <nhorman@redhat.com>
Date: Tue, 9 Dec 2008 21:48:02 -0500
Subject: Revert: [x86] disable hpet on machine_crash_shutdown
Message-id: 20081210024802.GE26089@hmsendeavour.rdu.redhat.com
O-Subject: Re: [RHEL5] patch: disable hpet on machine_crash_shutdown (bz 473038)
Bugzilla: 475652

On Fri, Dec 05, 2008 at 03:36:55PM -0500, Neil Horman wrote:
> Hey all-
> 	This is a backport of upstream commit
> 0c1b2724069951b1902373e688042b2ec382f68f.  It disables the hpet timer on kdump
> shutdown so as to prevent it from hanging the system during kdump reboot.
> Verified to fix bz 473038 on at least some of the systems listed (there are
> several).  Some of the listed systems still require the gart patch from bz
> 473166 which dchapman is working on.
>
> Regards
> Neil
>
>
Don, I apologize for this.  Doug Chapman discovered a regression with this
patch.  In my rush to get the HP XW systems up and running with kdump, I
neglected to consider if x86_64 system existed which don't have hpet timers
available.  As it happens, they do, and this patch makes them panic during kdump
shutdown.  Doug already has a patch for it put together, but at this later hour,
I think it would be better if we pulled this patch and deferred it for 5.4.

Regards & Apologies
Neil

diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c
index 0af4062..615878f 100644
--- a/arch/i386/kernel/crash.c
+++ b/arch/i386/kernel/crash.c
@@ -22,7 +22,6 @@
 #include <asm/nmi.h>
 #include <asm/hw_irq.h>
 #include <asm/apic.h>
-#include <asm/hpet.h>
 #include <mach_ipi.h>
 
 
@@ -179,9 +178,6 @@ void machine_crash_shutdown(struct pt_regs *regs)
 #if defined(CONFIG_X86_IO_APIC)
 	disable_IO_APIC();
 #endif
-#ifdef CONFIG_HPET_TIMER
-	hpet_disable();
-#endif
 #endif /* CONFIG_XEN */
 	crash_save_self(regs);
 }
diff --git a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
index 6f3989a..cf206c8 100644
--- a/arch/i386/kernel/time_hpet.c
+++ b/arch/i386/kernel/time_hpet.c
@@ -236,19 +236,6 @@ int is_hpet_capable(void)
 	return 0;
 }
 
-void hpet_disable(void)
-{
-        if (is_hpet_capable()) {
-                unsigned long cfg = hpet_readl(HPET_CFG);
-
-                if (is_hpet_legacy_int_enabled()) {
-                        cfg &= ~HPET_CFG_LEGACY;
-                }
-                cfg &= ~HPET_CFG_ENABLE;
-                hpet_writel(cfg, HPET_CFG);
-        }
-}
-
 static int __init hpet_setup(char* str)
 {
 	if (str) {
diff --git a/arch/x86_64/kernel/crash.c b/arch/x86_64/kernel/crash.c
index a66fc8e..178fb47 100644
--- a/arch/x86_64/kernel/crash.c
+++ b/arch/x86_64/kernel/crash.c
@@ -22,7 +22,6 @@
 #include <asm/hardirq.h>
 #include <asm/nmi.h>
 #include <asm/hw_irq.h>
-#include <asm/hpet.h>
 #include <asm/mach_apic.h>
 
 /* This keeps a track of which one is crashing cpu. */
@@ -162,9 +161,6 @@ static void nmi_shootdown_cpus(void)
 
 void machine_crash_shutdown(struct pt_regs *regs)
 {
-#ifdef CONFIG_HPET_TIMER
-	unsigned long cfg;
-#endif
 	/*
 	 * This function is only called after the system
 	 * has panicked or is otherwise in a critical state.
@@ -189,12 +185,6 @@ void machine_crash_shutdown(struct pt_regs *regs)
 #if defined(CONFIG_X86_IO_APIC)
 	disable_IO_APIC();
 #endif
-#ifdef CONFIG_HPET_TIMER
-	cfg = hpet_readl(HPET_CFG);
-	cfg &= ~HPET_CFG_LEGACY;
-	cfg &= ~HPET_CFG_ENABLE;
-	hpet_writel(cfg, HPET_CFG);
-#endif
 #endif /* CONFIG_XEN */
 	crash_save_self(regs);
 }
diff --git a/include/asm-i386/hpet.h b/include/asm-i386/hpet.h
index 969e5df..c72ffa7 100644
--- a/include/asm-i386/hpet.h
+++ b/include/asm-i386/hpet.h
@@ -96,7 +96,6 @@ extern int hpet_use_timer;
 
 extern int hpet_rtc_timer_init(void);
 extern int hpet_enable(void);
-extern void hpet_disable(void);
 extern int hpet_reenable(void);
 extern int is_hpet_enabled(void);
 extern int is_hpet_legacy_int_enabled(void);