cpuidle: Single/Global registration of idle states

This patch makes the cpuidle_states structure global (single copy)
instead of per-cpu. The statistics needed on per-cpu basis
by the governor are kept per-cpu. This simplifies the cpuidle
subsystem as state registration is done by single cpu only.
Having single copy of cpuidle_states saves memory. Rare case
of asymmetric C-states can be handled within the cpuidle driver
and architectures such as POWER do not have asymmetric C-states.

Having single/global registration of all the idle states,
dynamic C-state transitions on x86 are handled by
the boot cpu. Here, the boot cpu  would disable all the devices,
re-populate the states and later enable all the devices,
irrespective of the cpu that would receive the notification first.

Reference:
https://lkml.org/lkml/2011/4/25/83

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Trinabh Gupta <g.trinabh@gmail.com>
Tested-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 3 insertions, 17 deletions

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index a4e0f1ba6040..9d7bc9f6b6cc 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -426,7 +426,7 @@ static int acpi_cpu_soft_notify(struct notifier_block *nfb,
 
         if (action == CPU_ONLINE && pr) {
                 acpi_processor_ppc_has_changed(pr, 0);
-                acpi_processor_cst_has_changed(pr);
+                acpi_processor_hotplug(pr);
                 acpi_processor_reevaluate_tstate(pr, action);
                 acpi_processor_tstate_has_changed(pr);
         }
@@ -503,8 +503,7 @@ static int __cpuinit acpi_processor_add(struct acpi_device *device)
         acpi_processor_get_throttling_info(pr);
         acpi_processor_get_limit_info(pr);
 
-
-        if (cpuidle_get_driver() == &acpi_idle_driver)
+        if (!cpuidle_get_driver() || cpuidle_get_driver() == &acpi_idle_driver)
                 acpi_processor_power_init(pr, device);
 
         pr->cdev = thermal_cooling_device_register("Processor", device,
@@ -800,17 +799,9 @@ static int __init acpi_processor_init(void)
 
         memset(&errata, 0, sizeof(errata));
 
-        if (!cpuidle_register_driver(&acpi_idle_driver)) {
-                printk(KERN_DEBUG "ACPI: %s registered with cpuidle\n",
-                        acpi_idle_driver.name);
-        } else {
-                printk(KERN_DEBUG "ACPI: acpi_idle yielding to %s\n",
-                        cpuidle_get_driver()->name);
-        }
-
         result = acpi_bus_register_driver(&acpi_processor_driver);
         if (result < 0)
-                goto out_cpuidle;
+                return result;
 
         acpi_processor_install_hotplug_notify();
 
@@ -821,11 +812,6 @@ static int __init acpi_processor_init(void)
         acpi_processor_throttling_init();
 
         return 0;
-
-out_cpuidle:
-        cpuidle_unregister_driver(&acpi_idle_driver);
-
-        return result;
 }
 
 static void __exit acpi_processor_exit(void)