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Subject[PATCH 08/18] cpuidle: create bootparam "cpuidle.off=1"
Date
From: Len Brown <len.brown@intel.com>

useful for disabling cpuidle to fall back
to architecture-default idle loop

cpuidle drivers and governors will fail to register.
on x86 they'll say so:

intel_idle: intel_idle yielding to (null)
ACPI: acpi_idle yielding to (null)

Signed-off-by: Len Brown <len.brown@intel.com>
---
Documentation/kernel-parameters.txt | 3 +++
drivers/cpuidle/cpuidle.c | 10 ++++++++++
drivers/cpuidle/cpuidle.h | 1 +
drivers/cpuidle/driver.c | 3 +++
drivers/cpuidle/governor.c | 3 +++
5 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index f4a04c0..08e8a22 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -546,6 +546,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
/proc/<pid>/coredump_filter.
See also Documentation/filesystems/proc.txt.

+ cpuidle.off=1 [CPU_IDLE]
+ disable the cpuidle sub-system
+
cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Format:
<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index bf50924..faae2c3 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -28,6 +28,12 @@ LIST_HEAD(cpuidle_detected_devices);
static void (*pm_idle_old)(void);

static int enabled_devices;
+static int off __read_mostly;
+
+int cpuidle_disabled(void)
+{
+ return off;
+}

#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
static void cpuidle_kick_cpus(void)
@@ -427,6 +433,9 @@ static int __init cpuidle_init(void)
{
int ret;

+ if (cpuidle_disabled())
+ return -ENODEV;
+
pm_idle_old = pm_idle;

ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
@@ -438,4 +447,5 @@ static int __init cpuidle_init(void)
return 0;
}

+module_param(off, int, 0444);
core_initcall(cpuidle_init);
diff --git a/drivers/cpuidle/cpuidle.h b/drivers/cpuidle/cpuidle.h
index 33e50d5..38c3fd8 100644
--- a/drivers/cpuidle/cpuidle.h
+++ b/drivers/cpuidle/cpuidle.h
@@ -13,6 +13,7 @@ extern struct list_head cpuidle_governors;
extern struct list_head cpuidle_detected_devices;
extern struct mutex cpuidle_lock;
extern spinlock_t cpuidle_driver_lock;
+extern int cpuidle_disabled(void);

/* idle loop */
extern void cpuidle_install_idle_handler(void);
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index fd1601e..3f7e3ce 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -26,6 +26,9 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
if (!drv)
return -EINVAL;

+ if (cpuidle_disabled())
+ return -ENODEV;
+
spin_lock(&cpuidle_driver_lock);
if (cpuidle_curr_driver) {
spin_unlock(&cpuidle_driver_lock);
diff --git a/drivers/cpuidle/governor.c b/drivers/cpuidle/governor.c
index 724c164..ea2f8e7 100644
--- a/drivers/cpuidle/governor.c
+++ b/drivers/cpuidle/governor.c
@@ -81,6 +81,9 @@ int cpuidle_register_governor(struct cpuidle_governor *gov)
if (!gov || !gov->select)
return -EINVAL;

+ if (cpuidle_disabled())
+ return -ENODEV;
+
mutex_lock(&cpuidle_lock);
if (__cpuidle_find_governor(gov->name) == NULL) {
ret = 0;
--
1.7.5.rc0


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