From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com>
Currently all the idle states registered by a cpu-idle driver are
enabled by default. This patch adds a mechanism which allows the
driver to hint if an idle-state should start in a disabled state. The
cpu-idle core will use this hint to appropriately initialize the
usage->disable knob of the CPU device idle state.
The state can be enabled at run time by echo'ing a zero to the sysfs
"disable" control file.
Signed-off-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
---
drivers/cpuidle/cpuidle.c | 7 +++++++
include/linux/cpuidle.h | 7 ++++++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index c73207a..b4debc7 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -439,7 +439,14 @@ static void __cpuidle_unregister_device(struct
cpuidle_device *dev)
static void __cpuidle_device_init(struct cpuidle_device *dev)
{
+ struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+ int i;
+
memset(dev->states_usage, 0, sizeof(dev->states_usage));
+ for (i = 0; i < drv->state_count; i++) {
+ if (drv->states[i].disable_use_at_start)
+ dev->states_usage[i].disable = 1;
+ }
dev->last_residency = 0;
}
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index bb31373..f3fe855 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -44,7 +44,12 @@ struct cpuidle_state {
int power_usage; /* in mW */
unsigned int target_residency; /* in US */
bool disabled; /* disabled on all CPUs */
-
+ /*
+ * disable_use_at_start: If true, then this idle state will be
+ * disabled by default. It can be enabled at runtime using the
+ * per-cpu cpuidle sysfs control file named "disable".
+ */
+ bool disable_use_at_start;
int (*enter) (struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index);
--
1.9.4
