The mW data in this field comes from AML _CST,
which was typed in by a BIOS writer, and is thus
considered unreliable.

Linux does not use it for making any decisions.
We do display it in sysfs where somebody might
read it and assume it is meaningful, so delete it.
Signed-off-by: NLen Brown <len.brown@intel.com>

Looks like a left over from /proc/acpi/processor/*/power which got removed
Signed-off-by: NThomas Renninger <trenn@suse.de>
Signed-off-by: NLen Brown <len.brown@intel.com>

Some minor improvements in error handling, but overall it was mostly dead
code.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLen Brown <len.brown@intel.com>

Remove deprecated ACPI processor procfs I/F, including:
/proc/acpi/processor/CPUX/power
/proc/acpi/processor/CPUX/limit
/proc/acpi/processor/CPUX/info

/proc/acpi/processor/CPUX/throttling still exists,
as we don't have sysfs I/F available for now.
Signed-off-by: NZhang Rui <rui.zhang@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Accomodate the original C1E-aware idle routine to the different times
during boot when the BIOS enables C1E. While at it, remove the synthetic
CPUID flag in favor of a single global setting which denotes C1E status
on the system.

[ hpa: changed c1e_enabled to be a bool; clarified cpu bit 3:21 comment ]
Signed-off-by: NMichal Schmidt <mschmidt@redhat.com>
LKML-Reference: <20100727165335.GA11630@aftab>
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>

Now that all arches have been converted over to use generic time via
clocksources or arch_gettimeoffset(), we can remove the GENERIC_TIME
config option and simplify the generic code.
Signed-off-by: NJohn Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-4-git-send-email-johnstul@us.ibm.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

processor.bm_check_disable=1" prevents Linux from checking BM_STS
before entering C3-type cpu power states.

This may be useful for a system running acpi_idle
where the BIOS exports FADT C-states, _CST IO C-states,
or _CST FFH C-states with the BM_STS bit set;
while configuring the chipset to set BM_STS
more frequently than perhaps is optimal.

Note that such systems may have been developed
using a tickful OS that would quickly clear BM_STS,
rather than a tickless OS that may go for some time
between checking and clearing BM_STS.

Note also that an alternative for newer systems
is to use the intel_idle driver, which always
ignores BM_STS, relying Linux device drivers
to register constraints explicitly via PM_QOS.

https://bugzilla.kernel.org/show_bug.cgi?id=15886Signed-off-by: NLen Brown <len.brown@intel.com>

It turns out that there is a bit in the _CST for Intel FFH C3
that tells the OS if we should be checking BM_STS or not.

Linux has been unconditionally checking BM_STS.
If the chip-set is configured to enable BM_STS,
it can retard or completely prevent entry into
deep C-states -- as illustrated by turbostat:

http://userweb.kernel.org/~lenb/acpi/utils/pmtools/turbostat/

ref: Intel Processor Vendor-Specific ACPI Interface Specification
table 4 "_CST FFH GAS Field Encoding"
Bit 1: Set to 1 if OSPM should use Bus Master avoidance for this C-state

https://bugzilla.kernel.org/show_bug.cgi?id=15886Signed-off-by: NLen Brown <len.brown@intel.com>

CONFIG_ACPI_PROCFS=n:

drivers/acpi/processor_idle.c:83: warning: 'us_to_pm_timer_ticks' defined but not used.
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLen Brown <len.brown@intel.com>

acpi_enter_[simple|bm] routines does us to pm tick conversion on every
idle wakeup and the value is only used in /proc/acpi display. We can
store the time in us and convert it into pm ticks before printing instead and
avoid the conversion in the common path.
Signed-off-by: NVenkatesh Pallipadi <venki@google.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

The C-state idle time is not calculated correctly, which will return the wrong
residency time in C-state. It will have the following effects:
   1.  The system can't choose the deeper C-state when it is idle next time.
Of course the system power is increased. E.g. On one server machine about 40W
idle power is increased.
   2.  The powertop shows that it will stay in C0 running state about 95% time
although the system is idle at most time.

2.6.35-rc1 regression caused-by: 2da513f5
(ACPI: Minor cleanup eliminating redundant PMTIMER_TICKS to NS conversion)
Signed-off-by: NZhao Yakui <yakui.zhao@intel.com>
Reported-by: NYu Zhidong <zhidong.yu@intel.com>
Tested-by: NYu Zhidong <zhidong.yu@intel.com>
Acked-by: NVenkatesh Pallipadi <venki@google.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

acpi_enter_[simple,bm] does
idle timing in ns, convert it to timeval, then to us, then to
pmtimer_ticks and then back to ns.

This patch changes things to
idle timing in ns, convert it to us, and then to pmtimer_ticks.

Just saves an imul along this path, but makes the code cleaner.
Signed-off-by: NVenkatesh Pallipadi <venki@google.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

commit d306ebc2
(ACPI: Be in TS_POLLING state during mwait based C-state entry)
fixed an important power & performance issue where ACPI c2 and c3 C-states
were clearing TS_POLLING even when using MWAIT (ACPI_STATE_FFH).
That bug had been causing us to receive redundant scheduling interrups
when we had already been woken up by MONITOR/MWAIT.

Following up on that...

In the MWAIT case, we don't have to subsequently
check need_resched(), as that c heck was there
for the TS_POLLING-clearing case.

Note that not only does the cpuidle calling function
already check need_resched() before calling us, the
low-level entry into monitor/mwait calls it twice --
guaranteeing that a write to the trigger address
can not go un-noticed.

Also, in this case, we don't have to set TS_POLLING
when we wake, because we never cleared it.
Signed-off-by: NLen Brown <len.brown@intel.com>
Acked-by: NVenkatesh Pallipadi <venki@google.com>

These were used before cpuidle by the native ACPI idle driver,
which tracked promotion and demotion between states.

The code was referenced by CONFIG_ACPI_PROCFS
for /proc/acpi/processor/*/power,
but as we no longer do promotion/demotion, that
reference has been a NOP since the transition.
Signed-off-by: NLen Brown <len.brown@intel.com>

This patch changes the string based list management to a handle base
implementation to help with the hot path use of pm-qos, it also renames
much of the API to use "request" as opposed to "requirement" that was
used in the initial implementation.  I did this because request more
accurately represents what it actually does.

Also, I added a string based ABI for users wanting to use a string
interface.  So if the user writes 0xDDDDDDDD formatted hex it will be
accepted by the interface.  (someone asked me for it and I don't think
it hurts anything.)

This patch updates some documentation input I got from Randy.
Signed-off-by: Nmarkgross <mgross@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

ACPI deep C-state entry had a long standing bug/missing feature, wherein we were sending
resched IPIs when an idle CPU is in mwait based deep C-state. Only mwait based C1 was using
the write to the monitored address to wake up mwait'ing CPU.

This patch changes the code to retain TS_POLLING bit if we are entering an mwait based
deep C-state.

The patch has been verified to reduce the number of resched IPIs in general and also
improves the performance/power on workloads with low system utilization (i.e., when mwait based
deep C-states are being used).

Fixes "netperf ~50% regression with 2.6.33-rc1, bisect to 1b9508f6"
http://marc.info/?l=linux-kernel&m=126441481427331&w=4Reported-by: NLin Ming <ming.m.lin@intel.com>
Tested-by: NAlex Shi <alex.shi@intel.com>
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Since the rewrite of the CPU idle governor in 2.6.32, two laptops have
surfaced where the BIOS advertises a C2 power state, but for some reason
this state is not functioning (as verified in both cases by powertop
before the patch in .32).

The old governor had the accidental behavior that if a non-working state
was chosen too many times, it would end up falling back to C1.  The new
governor works differently and this accidental behavior is no longer
there; the result is a high temperature on these two machines.

This patch adds these 2 machines to the DMI table for C state anomalies;
by just not using C2 both these machines are better off (the TSC can be
used instead of the pm timer, giving a performance boost for example).

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=14742Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Reported-by: <akwatts@ymail.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLen Brown <len.brown@intel.com>

acpi_integer is now obsolete and removed from the ACPICA code base,
replaced by u64.
Signed-off-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

no functional change -- cleanup only.

acpi_processor_power_verify_c2() was nearly empty due to a previous patch,
so expand its remains into its one caller and delete it.
Signed-off-by: NLen Brown <len.brown@intel.com>

Do for C3 what the previous patch did for C2.

The C2 patch was in response to a highly visible
and multiply reported C-state/turbo failure,
while this change has no bug report in-hand.

This will enable C3 in Linux on systems where BIOS
overstates C3 latency in _CST.  It will also enable
future systems which may actually have C3 > 1000usec.

Linux has always ignored ACPI BIOS C3 with exit latency > 1000 usec,
and the ACPI spec is clear that is correct FADT-supplied C3.

However, the ACPI spec explicitly states that _CST-supplied C-states
have no latency limits.

So move the 1000usec C3 test out of the code shared
by FADT and _CST code-paths, and into the FADT-specific path.
Signed-off-by: NLen Brown <len.brown@intel.com>

Linux has always ignored ACPI BIOS C2 with exit latency > 100 usec,
and the ACPI spec is clear that is correct FADT-supplied C2.

However, the ACPI spec explicitly states that _CST-supplied C-states
have no latency limits.

So move the 100usec C2 test out of the code shared
by FADT and _CST code-paths, and into the FADT-specific path.

This bug has not been visible until Nehalem, which advertises
a CPU-C2 worst case exit latency on servers of 205usec.
That (incorrect) figure is being used by BIOS writers
on mobile Nehalem systems for the AC configuration.
Thus, Linux ignores C2 leaving just C1, which is
saves less power, and also impacts performance
by preventing the use of turbo mode.

http://bugzilla.kernel.org/show_bug.cgi?id=15064Tested-by: NAlex Chiang <achiang@hp.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

I got following warning on ia64 box:
  In function 'acpi_processor_power_verify':
  642: warning: passing argument 2 of 'smp_call_function_single' from
  incompatible pointer type

This smp_call_function_single() was introduced by a commit
f833bab8:

 > @@ -162,8 +162,9 @@
 >               pr->power.timer_broadcast_on_state = state;
 >  }
 >
 > -static void lapic_timer_propagate_broadcast(struct acpi_processor *pr)
 > +static void lapic_timer_propagate_broadcast(void *arg)
 >  {
 > +       struct acpi_processor *pr = (struct acpi_processor *) arg;
 >         unsigned long reason;
 >
 >         reason = pr->power.timer_broadcast_on_state < INT_MAX ?
 > @@ -635,7 +636,8 @@
 >                 working++;
 >         }
 >
 > -       lapic_timer_propagate_broadcast(pr);
 > +       smp_call_function_single(pr->id, lapic_timer_propagate_broadcast,
 > +                                pr, 1);
 >
 >         return (working);
 >  }

The problem is that the lapic_timer_propagate_broadcast() has 2 versions:
One is real code that modified in the above commit, and the other is NOP
code that used when !ARCH_APICTIMER_STOPS_ON_C3:

  static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) { }

So I got warning because of !ARCH_APICTIMER_STOPS_ON_C3.

We really want to do nothing here on !ARCH_APICTIMER_STOPS_ON_C3, so
modify lapic_timer_propagate_broadcast() of real version to use
smp_call_function_single() in it.
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Commit 3d5b6fb4 ("ACPI: Kill overly
verbose "power state" log messages") removed the actual use of this
variable, but didn't remove the variable itself, resulting in build
warnings like

  drivers/acpi/processor_idle.c: In function ‘acpi_processor_power_init’:
  drivers/acpi/processor_idle.c:1169: warning: unused variable ‘i’

Just get rid of the now unused variable.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I was recently lucky enough to get a 64-CPU system, so my kernel log
ends up with 64 lines like:

    ACPI: CPU0 (power states: C1[C1] C2[C3])

This is pretty useless clutter because this info is already available
after boot from both /sys/devices/system/cpu/cpu*/cpuidle/state?/ as
well as /proc/acpi/processor/CPU*/power.

So just delete the code that prints the C-states in processor_idle.c.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Linux/ACPI core files using internal.h all PREFIX "ACPI: ",
however, not all ACPI drivers use/want it -- and they
should not have to #undef PREFIX to define their own.

Add GPL commment to internal.h while we are there.

This does not change any actual console output,
asside from a whitespace fix.
Signed-off-by: NLen Brown <len.brown@intel.com>

Currently clockevents_notify() is called with interrupts enabled at
some places and interrupts disabled at some other places.

This results in a deadlock in this scenario.

cpu A holds clockevents_lock in clockevents_notify() with irqs enabled
cpu B waits for clockevents_lock in clockevents_notify() with irqs disabled
cpu C doing set_mtrr() which will try to rendezvous of all the cpus.

This will result in C and A come to the rendezvous point and waiting
for B. B is stuck forever waiting for the spinlock and thus not
reaching the rendezvous point.

Fix the clockevents code so that clockevents_lock is taken with
interrupts disabled and thus avoid the above deadlock.

Also call lapic_timer_propagate_broadcast() on the destination cpu so
that we avoid calling smp_call_function() in the clockevents notifier
chain.

This issue left us wondering if we need to change the MTRR rendezvous
logic to use stop machine logic (instead of smp_call_function) or add
a check in spinlock debug code to see if there are other spinlocks
which gets taken under both interrupts enabled/disabled conditions.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: "Pallipadi Venkatesh" <venkatesh.pallipadi@intel.com>
Cc: "Brown Len" <len.brown@intel.com>
LKML-Reference: <1250544899.2709.210.camel@sbs-t61.sc.intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

drivers/acpi/processor_idle.c:1162: warning: unused variable ‘entry’
Signed-off-by: NLen Brown <len.brown@intel.com>

Now whether the ACPI processor proc I/F is registered depends on the
CONFIG_PROC. It had better depend on the CONFIG_ACPI_PROCFS.
When the CONFIG_ACPI_PROCFS is unset in kernel configuration, the
ACPI processor proc I/F won't be registered.
Signed-off-by: NZhao Yakui <yakui.zhao@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

cosmetic only.  The lapic_timer workaround routines
are specific to the lapic_timer, and are not acpi-generic.

old:

acpi_timer_check_state()
acpi_propagate_timer_broadcast()
acpi_state_timer_broadcast()

new:

lapic_timer_check_state()
lapic_timer_propagate_broadcast()
lapic_timer_state_broadcast()

also, simplify the code in acpi_processor_power_verify()
so that lapic_timer_check_state() is simply called
from one place for all valid C-states, including C1.
Signed-off-by: NLen Brown <len.brown@intel.com>

ARB_DISABLE is a NOP on all of the recent Intel platforms.

For such platforms, reduce contention on c3_lock
by skipping the fake ARB_DISABLE.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

When AMD C1E is enabled, local APIC timer will stop even in C1. To avoid
suspend/resume hang, this patch removes C1 and replace it with a cpu_relax() in
suspend/resume path. This hasn't any impact in runtime path.

http://bugzilla.kernel.org/show_bug.cgi?id=13233

[ impact: avoid suspend/resume hang in AMD CPU with C1E enabled ]
Tested-by: NDmitry Lyzhyn <thisistempbox@yahoo.com>
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

When AMD C1E is enabled, local APIC timer will stop even in C1.
This patch uses broadcast IPI to replace local APIC timer in C1.

http://bugzilla.kernel.org/show_bug.cgi?id=13233

[ impact: avoid boot hang in AMD CPU with C1E enabled ]
Tested-by: NDmitry Lyzhyn <thisistempbox@yahoo.com>
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Processor idle power states C2 and C3 stop the TSC on many machines.
Linux recognizes this situation and marks the TSC as unstable:

Marking TSC unstable due to TSC halts in idle

But if those same machines are booted with "processor.max_cstate=1",
then there is no need to validate C2 and C3, and no need to
disable the TSC, which can be reliably used as a clocksource.
Signed-off-by: NLen Brown <len.brown@intel.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>

A previous 2.6.30 patch, a71e4917,
(ACPI: idle: mark_tsc_unstable() at init-time, not run-time)
erroneously disabled the TSC on systems that did not actually
have valid deep C-states.

Move the check after the deep-C-states are validated,
via new helper, tsc_check_state(), hich replaces tsc_halts_in_c().
Signed-off-by: NLen Brown <len.brown@intel.com>
Acked-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NFrans Pop <elendil@planet.nl>

In 2.6.29,
31878dd8
"ACPI: remove BM_RLD access from idle entry path"
moved BM_RLD initialization to init-time from run time.

But we discovered that some BIOS do not restore BM_RLD
after suspend, causing device errors on C3 and C4
after resume.  So now the kernel restores BM_RLD.

http://bugzilla.kernel.org/show_bug.cgi?id=13032Signed-off-by: NLen Brown <len.brown@intel.com>

We had a disable/enable around acpi_idle_do_entry() due to an erratum
in an early prototype CPU i had access to. That erratum has been fixed
in the BIOS so remove the quirk.

The quirk also kept us from profiling interrupts that hit the ACPI idle
instruction - so this is an improvement as well, beyond a cleanup and
a micro-optimization.

[ Impact: improve profiling scope, cleanup, micro-optimization ]
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The current disable/enable mechanism is:

	token = hw_perf_save_disable();
	...
	/* do bits */
	...
	hw_perf_restore(token);

This works well, provided that the use nests properly. Except we don't.

x86 NMI/INT throttling has non-nested use of this, breaking things. Therefore
provide a reference counter disable/enable interface, where the first disable
disables the hardware, and the last enable enables the hardware again.

[ Impact: refactor, simplify the PMU disable/enable logic ]
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

As processor.max_cstate is an init-time-only modparam,
sanity checking it at init-time is sufficient.

http://bugzilla.kernel.org/show_bug.cgi?id=13142Signed-off-by: NLen Brown <len.brown@intel.com>

Linux tells ICH4 users that they can (manually) invoke
"hpet=force" to enable the undocumented ICH-4M HPET.
The HPET becomes available for both clocksource and clockevents.

But as of ff69f2bb
(acpi: fix of pmtimer overflow that make Cx states time incorrect)
the HPET may be used via clocksource for idle accounting, and
hpet=force on an ICH4 box hangs boot.

It turns out that touching the MMIO HPET withing
the ARB_DIS part of C3 will hang the hardware.

The fix is to simply move the timer access outside
the ARB_DIS region.  This is a no-op on modern hardware
because ARB_DIS is no longer used.

http://bugzilla.kernel.org/show_bug.cgi?id=13087Acked-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>