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cpuidle: Single/Global registration of idle states

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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>
This commit is contained in:
Deepthi Dharwar
2011-10-28 16:20:42 +05:30
committed by Len Brown
parent 4202735e8a
commit 46bcfad7a8
16 changed files with 438 additions and 206 deletions
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31
arch/arm/mach-at91/cpuidle.c
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@@ -33,6 +33,7 @@ static struct cpuidle_driver at91_idle_driver = {
/* Actual code that puts the SoC in different idle states */
static int at91_enter_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
struct timeval before, after;
@@ -64,27 +65,29 @@ static int at91_enter_idle(struct cpuidle_device *dev,
static int at91_init_cpuidle(void)
{
struct cpuidle_device *device;
cpuidle_register_driver(&at91_idle_driver);
struct cpuidle_driver *driver = &at91_idle_driver;
device = &per_cpu(at91_cpuidle_device, smp_processor_id());
device->state_count = AT91_MAX_STATES;
driver->state_count = AT91_MAX_STATES;
/* Wait for interrupt state */
device->states[0].enter = at91_enter_idle;
device->states[0].exit_latency = 1;
device->states[0].target_residency = 10000;
device->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(device->states[0].name, "WFI");
strcpy(device->states[0].desc, "Wait for interrupt");
driver->states[0].enter = at91_enter_idle;
driver->states[0].exit_latency = 1;
driver->states[0].target_residency = 10000;
driver->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(driver->states[0].name, "WFI");
strcpy(driver->states[0].desc, "Wait for interrupt");
/* Wait for interrupt and RAM self refresh state */
device->states[1].enter = at91_enter_idle;
device->states[1].exit_latency = 10;
device->states[1].target_residency = 10000;
device->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(device->states[1].name, "RAM_SR");
strcpy(device->states[1].desc, "WFI and RAM Self Refresh");
driver->states[1].enter = at91_enter_idle;
driver->states[1].exit_latency = 10;
driver->states[1].target_residency = 10000;
driver->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(driver->states[1].name, "RAM_SR");
strcpy(driver->states[1].desc, "WFI and RAM Self Refresh");
cpuidle_register_driver(&at91_idle_driver);
if (cpuidle_register_device(device)) {
printk(KERN_ERR "at91_init_cpuidle: Failed registering\n");