ACPI / PM: Leave Bus Master Arbitration enabled for suspend/resume

This is an old suspend/resume lockup fix:

	commit 2780cc4660e1
	Author: Len Brown <len.brown@intel.com>
	Date:   Thu Dec 23 13:43:30 2004 -0500

	    [ACPI] Fix suspend/resume lockup issue
	    by leaving Bus Master Arbitration enabled.
	    The ACPI spec mandates it be disabled only for C3.

	    http://bugzilla.kernel.org/show_bug.cgi?id=3599

	    Signed-off-by: David Shaohua Li <shaohua.li@intel.com>
	    Signed-off-by: Len Brown <len.brown@intel.com>

The bug snuck back in in commit 2feec47d4c5f (ACPICA: ACPI 5: Support
for new FADT SleepStatus, SleepControl registers, 2012-02-14),
presumably by copy/pasting a copy of the code without that fix for the
legacy case.

On affected machines, after that commit, the machine locks up hard on
resume from suspend.  The same fix as seven years ago still works.

Addresses <https://bugzilla.kernel.org/show_bug.cgi?id=43641>.

Reported-bisected-and-tested-by: Octavio Alvarez <alvarezp@alvarezp.com>
Reported-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
PM / cpuidle: System resume hang fix with cpuidle

On certain bios, resume hangs if cpus are allowed to enter idle states
during suspend [1].

This was fixed in apci idle driver [2].But intel_idle driver does not
have this fix. Thus instead of replicating the fix in both the idle
drivers, or in more platform specific idle drivers if needed, the
more general cpuidle infrastructure could handle this.

A suspend callback in cpuidle_driver could handle this fix. But
a cpuidle_driver provides only basic functionalities like platform idle
state detection capability and mechanisms to support entry and exit
into CPU idle states. All other cpuidle functions are found in the
cpuidle generic infrastructure for good reason that all cpuidle
drivers, irrepective of their platforms will support these functions.

One option therefore would be to register a suspend callback in cpuidle
which handles this fix. This could be called through a PM_SUSPEND_PREPARE
notifier. But this is too generic a notfier for a driver to handle.

Also, ideally the job of cpuidle is not to handle side effects of suspend.
It should expose the interfaces which "handle cpuidle 'during' suspend"
or any other operation, which the subsystems call during that respective
operation.

The fix demands that during suspend, no cpus should be allowed to enter
deep C-states. The interface cpuidle_uninstall_idle_handler() in cpuidle
ensures that. Not just that it also kicks all the cpus which are already
in idle out of their idle states which was being done during cpu hotplug
through a CPU_DYING_FROZEN callbacks.

Now the question arises about when during suspend should
cpuidle_uninstall_idle_handler() be called. Since we are dealing with
drivers it seems best to call this function during dpm_suspend().
Delaying the call till dpm_suspend_noirq() does no harm, as long as it is
before cpu_hotplug_begin() to avoid race conditions with cpu hotpulg
operations. In dpm_suspend_noirq(), it would be wise to place this call
before suspend_device_irqs() to avoid ugly interactions with the same.

Ananlogously, during resume.

References:
[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/674075.
[2] http://marc.info/?l=linux-pm&m=133958534231884&w=2

Reported-and-tested-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>