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Commit 9ccdac36 authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[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: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 915166d9

arch/arm/kernel/process.c

+32 −26
Original line number Diff line number Diff line
@@ -114,9 +114,6 @@ void arm_machine_restart(char mode, const char *cmd) 
/*

 * 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 @@ EXPORT_SYMBOL_GPL(arm_pm_restart); 
 */

static void default_idle(void)

{

	if (hlt_counter)

		cpu_relax();

	else {

		local_irq_disable();

	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 @@ void cpu_idle(void) 


	/* endless idle loop with no priority at all */

	while (1) {

		void (*idle)(void) = pm_idle;



#ifdef CONFIG_HOTPLUG_CPU

		if (cpu_is_offline(smp_processor_id())) {

		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()))

				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();