[ARM] idle: clean up pm_idle calling, obey hlt_counter
pm_idle is used by infrastructure (eg, cpuidle) which expects architectures
to call it in a certain way. Arrange for ARM to follow x86's lead on this
and call pm_idle() with interrupts already disabled. However, we expect
pm_idle() to enable interrupts before it returns.
Also, OMAP wants to be able to disable hlt-ing, so allow hlt_counter to
prevent all calls to pm_idle.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 56820cc..39196df 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -114,9 +114,6 @@
/*
* Function pointers to optional machine specific functions
*/
-void (*pm_idle)(void);
-EXPORT_SYMBOL(pm_idle);
-
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);
@@ -130,20 +127,19 @@
*/
static void default_idle(void)
{
- if (hlt_counter)
- cpu_relax();
- else {
- local_irq_disable();
- if (!need_resched())
- arch_idle();
- local_irq_enable();
- }
+ if (!need_resched())
+ arch_idle();
+ local_irq_enable();
}
+void (*pm_idle)(void) = default_idle;
+EXPORT_SYMBOL(pm_idle);
+
/*
- * The idle thread. We try to conserve power, while trying to keep
- * overall latency low. The architecture specific idle is passed
- * a value to indicate the level of "idleness" of the system.
+ * The idle thread, has rather strange semantics for calling pm_idle,
+ * but this is what x86 does and we need to do the same, so that
+ * things like cpuidle get called in the same way. The only difference
+ * is that we always respect 'hlt_counter' to prevent low power idle.
*/
void cpu_idle(void)
{
@@ -151,21 +147,31 @@
/* endless idle loop with no priority at all */
while (1) {
- void (*idle)(void) = pm_idle;
-
+ tick_nohz_stop_sched_tick(1);
+ leds_event(led_idle_start);
+ while (!need_resched()) {
#ifdef CONFIG_HOTPLUG_CPU
- if (cpu_is_offline(smp_processor_id())) {
- leds_event(led_idle_start);
- cpu_die();
- }
+ if (cpu_is_offline(smp_processor_id()))
+ cpu_die();
#endif
- if (!idle)
- idle = default_idle;
- leds_event(led_idle_start);
- tick_nohz_stop_sched_tick(1);
- while (!need_resched())
- idle();
+ local_irq_disable();
+ if (hlt_counter) {
+ local_irq_enable();
+ cpu_relax();
+ } else {
+ stop_critical_timings();
+ pm_idle();
+ start_critical_timings();
+ /*
+ * This will eventually be removed - pm_idle
+ * functions should always return with IRQs
+ * enabled.
+ */
+ WARN_ON(irqs_disabled());
+ local_irq_enable();
+ }
+ }
leds_event(led_idle_end);
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();