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[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>
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1 changed files with 32 additions and 26 deletions
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@ -114,9 +114,6 @@ void arm_machine_restart(char mode, const char *cmd)
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/*
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* Function pointers to optional machine specific functions
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*/
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void (*pm_idle)(void);
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EXPORT_SYMBOL(pm_idle);
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void (*pm_power_off)(void);
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EXPORT_SYMBOL(pm_power_off);
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@ -130,20 +127,19 @@ EXPORT_SYMBOL_GPL(arm_pm_restart);
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*/
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static void default_idle(void)
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{
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if (hlt_counter)
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cpu_relax();
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else {
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local_irq_disable();
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if (!need_resched())
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arch_idle();
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local_irq_enable();
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}
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if (!need_resched())
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arch_idle();
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local_irq_enable();
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}
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void (*pm_idle)(void) = default_idle;
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EXPORT_SYMBOL(pm_idle);
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/*
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* The idle thread. We try to conserve power, while trying to keep
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* overall latency low. The architecture specific idle is passed
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* a value to indicate the level of "idleness" of the system.
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* The idle thread, has rather strange semantics for calling pm_idle,
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* but this is what x86 does and we need to do the same, so that
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* things like cpuidle get called in the same way. The only difference
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* is that we always respect 'hlt_counter' to prevent low power idle.
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*/
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void cpu_idle(void)
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{
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@ -151,21 +147,31 @@ void cpu_idle(void)
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/* endless idle loop with no priority at all */
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while (1) {
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void (*idle)(void) = pm_idle;
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tick_nohz_stop_sched_tick(1);
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leds_event(led_idle_start);
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while (!need_resched()) {
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#ifdef CONFIG_HOTPLUG_CPU
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if (cpu_is_offline(smp_processor_id())) {
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leds_event(led_idle_start);
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cpu_die();
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}
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if (cpu_is_offline(smp_processor_id()))
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cpu_die();
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#endif
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if (!idle)
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idle = default_idle;
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leds_event(led_idle_start);
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tick_nohz_stop_sched_tick(1);
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while (!need_resched())
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idle();
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local_irq_disable();
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if (hlt_counter) {
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local_irq_enable();
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cpu_relax();
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} else {
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stop_critical_timings();
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pm_idle();
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start_critical_timings();
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/*
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* This will eventually be removed - pm_idle
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* functions should always return with IRQs
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* enabled.
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*/
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WARN_ON(irqs_disabled());
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local_irq_enable();
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}
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}
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leds_event(led_idle_end);
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tick_nohz_restart_sched_tick();
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preempt_enable_no_resched();
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