diff --git a/arch/sh/include/asm/bugs.h b/arch/sh/include/asm/bugs.h index 46260fcbdf4b..02a19a1c033a 100644 --- a/arch/sh/include/asm/bugs.h +++ b/arch/sh/include/asm/bugs.h @@ -14,11 +14,15 @@ #include +extern void select_idle_routine(void); + static void __init check_bugs(void) { extern unsigned long loops_per_jiffy; char *p = &init_utsname()->machine[2]; /* "sh" */ + select_idle_routine(); + current_cpu_data.loops_per_jiffy = loops_per_jiffy; switch (current_cpu_data.family) { diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c index 27ff2dc093c7..8e61241230cb 100644 --- a/arch/sh/kernel/idle.c +++ b/arch/sh/kernel/idle.c @@ -21,7 +21,7 @@ #include static int hlt_counter; -void (*pm_idle)(void); +void (*pm_idle)(void) = NULL; void (*pm_power_off)(void); EXPORT_SYMBOL(pm_power_off); @@ -39,41 +39,68 @@ static int __init hlt_setup(char *__unused) } __setup("hlt", hlt_setup); -void default_idle(void) +static inline int hlt_works(void) { - if (!hlt_counter) { - clear_thread_flag(TIF_POLLING_NRFLAG); - smp_mb__after_clear_bit(); - set_bl_bit(); - stop_critical_timings(); - - while (!need_resched()) - cpu_sleep(); - - start_critical_timings(); - clear_bl_bit(); - set_thread_flag(TIF_POLLING_NRFLAG); - } else - while (!need_resched()) - cpu_relax(); + 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_works()) { + clear_thread_flag(TIF_POLLING_NRFLAG); + smp_mb__after_clear_bit(); + + if (!need_resched()) { + local_irq_enable(); + cpu_sleep(); + } + + set_thread_flag(TIF_POLLING_NRFLAG); + } else + 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; - - if (!idle) - idle = default_idle; - tick_nohz_stop_sched_tick(1); - while (!need_resched()) - idle(); - tick_nohz_restart_sched_tick(); + while (!need_resched() && cpu_online(cpu)) { + 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(); @@ -81,6 +108,20 @@ void cpu_idle(void) } } +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) { }