From 46bcfad7a819bd17ac4e831b04405152d59784ab Mon Sep 17 00:00:00 2001 From: Deepthi Dharwar Date: Fri, 28 Oct 2011 16:20:42 +0530 Subject: 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 Signed-off-by: Trinabh Gupta Tested-by: Jean Pihet Reviewed-by: Kevin Hilman Acked-by: Arjan van de Ven Acked-by: Kevin Hilman Signed-off-by: Len Brown --- drivers/cpuidle/driver.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'drivers/cpuidle/driver.c') diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c index 3f7e3cedd13..284d7af5a9c 100644 --- a/drivers/cpuidle/driver.c +++ b/drivers/cpuidle/driver.c @@ -17,6 +17,30 @@ static struct cpuidle_driver *cpuidle_curr_driver; DEFINE_SPINLOCK(cpuidle_driver_lock); +static void __cpuidle_register_driver(struct cpuidle_driver *drv) +{ + int i; + /* + * cpuidle driver should set the drv->power_specified bit + * before registering if the driver provides + * power_usage numbers. + * + * If power_specified is not set, + * we fill in power_usage with decreasing values as the + * cpuidle code has an implicit assumption that state Cn + * uses less power than C(n-1). + * + * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned + * an power value of -1. So we use -2, -3, etc, for other + * c-states. + */ + if (!drv->power_specified) { + for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) + drv->states[i].power_usage = -1 - i; + } +} + + /** * cpuidle_register_driver - registers a driver * @drv: the driver @@ -34,6 +58,7 @@ int cpuidle_register_driver(struct cpuidle_driver *drv) spin_unlock(&cpuidle_driver_lock); return -EBUSY; } + __cpuidle_register_driver(drv); cpuidle_curr_driver = drv; spin_unlock(&cpuidle_driver_lock); -- cgit v1.2.3-18-g5258