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Diffstat (limited to 'arch/sh/kernel/idle.c')
-rw-r--r--arch/sh/kernel/idle.c78
1 files changed, 61 insertions, 17 deletions
diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c
index 27ff2dc093c..aaff0037fcd 100644
--- a/arch/sh/kernel/idle.c
+++ b/arch/sh/kernel/idle.c
@@ -21,7 +21,7 @@
#include <asm/atomic.h>
static int hlt_counter;
-void (*pm_idle)(void);
+void (*pm_idle)(void) = NULL;
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);
@@ -39,48 +39,92 @@ static int __init hlt_setup(char *__unused)
}
__setup("hlt", hlt_setup);
+static inline int hlt_works(void)
+{
+ return !hlt_counter;
+}
+
+/*
+ * On SMP it's slightly faster (but much more power-consuming!)
+ * to poll the ->work.need_resched flag instead of waiting for the
+ * cross-CPU IPI to arrive. Use this option with caution.
+ */
+static void poll_idle(void)
+{
+ local_irq_enable();
+ while (!need_resched())
+ cpu_relax();
+}
+
void default_idle(void)
{
- if (!hlt_counter) {
+ if (hlt_works()) {
clear_thread_flag(TIF_POLLING_NRFLAG);
smp_mb__after_clear_bit();
- set_bl_bit();
- stop_critical_timings();
- while (!need_resched())
+ if (!need_resched()) {
+ local_irq_enable();
cpu_sleep();
+ } else
+ local_irq_enable();
- start_critical_timings();
- clear_bl_bit();
set_thread_flag(TIF_POLLING_NRFLAG);
} else
- while (!need_resched())
- cpu_relax();
+ poll_idle();
}
+/*
+ * The idle thread. There's no useful work to be done, so just try to conserve
+ * power and have a low exit latency (ie sit in a loop waiting for somebody to
+ * say that they'd like to reschedule)
+ */
void cpu_idle(void)
{
+ unsigned int cpu = smp_processor_id();
+
set_thread_flag(TIF_POLLING_NRFLAG);
/* endless idle loop with no priority at all */
while (1) {
- void (*idle)(void) = pm_idle;
+ tick_nohz_stop_sched_tick(1);
- if (!idle)
- idle = default_idle;
+ while (!need_resched() && cpu_online(cpu)) {
+ check_pgt_cache();
+ rmb();
- tick_nohz_stop_sched_tick(1);
- while (!need_resched())
- idle();
- tick_nohz_restart_sched_tick();
+ local_irq_disable();
+ /* Don't trace irqs off for idle */
+ stop_critical_timings();
+ pm_idle();
+ /*
+ * Sanity check to ensure that pm_idle() returns
+ * with IRQs enabled
+ */
+ WARN_ON(irqs_disabled());
+ start_critical_timings();
+ }
+ tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();
preempt_disable();
- check_pgt_cache();
}
}
+void __cpuinit select_idle_routine(void)
+{
+ /*
+ * If a platform has set its own idle routine, leave it alone.
+ */
+ if (pm_idle)
+ return;
+
+ if (hlt_works())
+ pm_idle = default_idle;
+ else
+ pm_idle = poll_idle;
+}
+
static void do_nothing(void *unused)
{
}