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Subject[PATCH 2/3] cpuidle: allow setting deepest idle
Date
When idle injection is used to cap power, we need to override
governor's choice of idle states. This patch allows caller to select
the deepest idle state on a CPU therefore achieve the maximum
potential power saving.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
drivers/cpuidle/cpuidle.c | 12 ++++++++++++
include/linux/cpuidle.h | 4 +++-
kernel/sched/idle.c | 3 +++
3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index c73207a..9ad45b3 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -97,6 +97,18 @@ static int find_deepest_state(struct cpuidle_driver *drv,
return ret;
}

+/* Set the current cpu to use the deepest idle state, override governors */
+void cpuidle_use_deepest_state(bool enable)
+{
+ struct cpuidle_device *dev;
+
+ preempt_disable();
+ dev = cpuidle_get_device();
+ dev->use_deepest_state = enable;
+ preempt_enable();
+}
+EXPORT_SYMBOL_GPL(cpuidle_use_deepest_state);
+
#ifdef CONFIG_SUSPEND
/**
* cpuidle_find_deepest_state - Find the deepest available idle state.
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index bb31373..7f93c63 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -74,6 +74,7 @@ struct cpuidle_state {
struct cpuidle_device {
unsigned int registered:1;
unsigned int enabled:1;
+ unsigned int use_deepest_state:1;
unsigned int cpu;

int last_residency;
@@ -192,11 +193,12 @@ static inline struct cpuidle_driver *cpuidle_get_cpu_driver(
static inline struct cpuidle_device *cpuidle_get_device(void) {return NULL; }
#endif

-#if defined(CONFIG_CPU_IDLE) && defined(CONFIG_SUSPEND)
+#if defined(CONFIG_CPU_IDLE)
extern int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev);
extern int cpuidle_enter_freeze(struct cpuidle_driver *drv,
struct cpuidle_device *dev);
+extern void cpuidle_use_deepest_state(bool enable);
#else
static inline int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
struct cpuidle_device *dev)
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index ffd9a83..fc65147 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -173,6 +173,9 @@ static void cpuidle_idle_call(void)

next_state = cpuidle_find_deepest_state(drv, dev);
call_cpuidle(drv, dev, next_state);
+ } else if (dev->use_deepest_state) {
+ next_state = cpuidle_find_deepest_state(drv, dev);
+ call_cpuidle(drv, dev, next_state);
} else {
/*
* Ask the cpuidle framework to choose a convenient idle state.
--
1.9.1
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