ACPI / hotplug / PCI: Avoid doing too much for spurious notifies

Sometimes we may get a spurious device check or bus check notify for
a hotplug device and in those cases we should avoid doing all of the
configuration work needed when something actually changes.  To that
end, check the return value of pci_scan_slot() in enable_slot() and
bail out early if it is 0.

This turns out to help reduce the amount of diagnostic output from
the ACPIPHP subsystem and speed up boot on at least one system that
generates multiple device check notifies for PCIe devices on the root
bus during boot.

Reported-and-tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / hotplug / PCI: Use _OST to notify firmware about notify status

The spec suggests that we should use _OST to notify the platform
about the status of notifications it sends us, for example so that
it doesn't repeate a notification that has been handled already.

This turns out to help reduce the amount of diagnostic output from
the ACPIPHP subsystem and speed up boot on at least one system that
generates multiple device check notifies for PCIe devices on the root
bus during boot.

Reported-and-tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'acpi-pci-hotplug-next' into bleeding-edge

* acpi-pci-hotplug-next:
  ACPI / hotplug / PCI: Use _OST to notify firmware about notify status
  ACPI / hotplug / PCI: Avoid doing too much for spurious notifies
Merge branch 'for-3.13' into bleeding-edge

* for-3.13:
  ARM: EXYNOS: convert cpuidle driver to be a platform driver
  intel_idle: mark some functions with __init tag
  intel_idle: mark states tables with __initdata tag
  intel_idle: shrink states tables
  ACPI / processor: Remove outdated comments
  ACPI / processor: remove unnecessary if (!pr) check
  ACPI / processor: remove some dead code in acpi_processor_get_info()
  x86 / ACPI: simplify _acpi_map_lsapic()
  ACPI / processor: use apic_id and remove duplicated _MAT evaluation
  ACPI / processor: Introduce apic_id in struct processor to save parsed APIC id
  ACP / fan: trivial style cleanup
  ACPI / processor: remove superfluous pr == NULL checks
  ACPI / mm: use NUMA_NO_NODE
  hotplug / powerpc / x86: Remove cpu_hotplug_driver_lock()
  hotplug / x86: Disable ARCH_CPU_PROBE_RELEASE on x86
  hotplug / x86: Add hotplug lock to missing places
  hotplug / x86: Fix online state in cpu0 debug interface

Conflicts:
	drivers/base/cpu.c