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Commit 10034aab authored by Russell King's avatar Russell King
Browse files

ARM: localtimer: clean up local timer on hot unplug 



When a CPU is hot unplugged, the generic tick code cleans up the
clock event device, but fails to call down to the device's set_mode
function to actually shut the device down.

To work around this, we've historically had a local_timer_stop()
callback out of the hotplug code.  However, this adds needless
complexity when we have the clock event device itself available.

Explicitly call the clock event device's set_mode function with
CLOCK_EVT_MODE_UNUSED, so that the hardware can be cleanly shutdown
without any special external callbacks.  When/if the generic code
is fixed, percpu_timer_stop() can be killed off.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent e3d9c625

arch/arm/include/asm/localtimer.h

+0 −12
Original line number Diff line number Diff line
@@ -30,7 +30,6 @@ asmlinkage void do_local_timer(struct pt_regs *); 
#include "smp_twd.h"



#define local_timer_ack()	twd_timer_ack()

#define local_timer_stop()	twd_timer_stop()



#else
@@ -40,11 +39,6 @@ asmlinkage void do_local_timer(struct pt_regs *); 
 */

int local_timer_ack(void);



/*

 * Stop a local timer interrupt.

 */

void local_timer_stop(void);



#endif



/*
@@ -52,12 +46,6 @@ void local_timer_stop(void); 
 */

void local_timer_setup(struct clock_event_device *);



#else



static inline void local_timer_stop(void)

{

}



#endif



#endif

arch/arm/include/asm/smp_twd.h

+0 −1
Original line number Diff line number Diff line
@@ -22,7 +22,6 @@ struct clock_event_device; 


extern void __iomem *twd_base;



void twd_timer_stop(void);

int twd_timer_ack(void);

void twd_timer_setup(struct clock_event_device *);

arch/arm/kernel/smp.c

+18 −1
Original line number Diff line number Diff line
@@ -189,6 +189,8 @@ int __cpuinit __cpu_up(unsigned int cpu) 
}



#ifdef CONFIG_HOTPLUG_CPU

static void percpu_timer_stop(void);



/*

 * __cpu_disable runs on the processor to be shutdown.

 */
@@ -216,7 +218,7 @@ int __cpu_disable(void) 
	/*

	 * Stop the local timer for this CPU.

	 */

	local_timer_stop();

	percpu_timer_stop();



	/*

	 * Flush user cache and TLB mappings, and then remove this CPU
@@ -539,6 +541,21 @@ void __cpuinit percpu_timer_setup(void) 
	local_timer_setup(evt);

}



#ifdef CONFIG_HOTPLUG_CPU

/*

 * The generic clock events code purposely does not stop the local timer

 * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it

 * manually here.

 */

static void percpu_timer_stop(void)

{

	unsigned int cpu = smp_processor_id();

	struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);



	evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);

}

#endif



static DEFINE_SPINLOCK(stop_lock);



/*

arch/arm/kernel/smp_twd.c

+0 −10
Original line number Diff line number Diff line
@@ -150,13 +150,3 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk) 


	clockevents_register_device(clk);

}
 


#ifdef CONFIG_HOTPLUG_CPU

/*

 * take a local timer down

 */

void twd_timer_stop(void)

{

	__raw_writel(0, twd_base + TWD_TIMER_CONTROL);

}

#endif