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Commit 20e91268 authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Russell King
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[ARM] 2863/1: clarify comment in PXA2xx and SA1x00 timer code 



Patch from Nicolas Pitre

Signed-off-by: default avatarNicolas Pitre <nico@cam.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 5c53ff08

arch/arm/mach-pxa/time.c

+4 −3
Original line number Original line Diff line number Diff line
@@ -91,9 +91,10 @@ pxa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) 




	/* Loop until we get ahead of the free running timer.

	/* Loop until we get ahead of the free running timer.

	 * This ensures an exact clock tick count and time accuracy.

	 * This ensures an exact clock tick count and time accuracy.

	 * IRQs are disabled inside the loop to ensure coherence between

	 * Since IRQs are disabled at this point, coherence between

	 * lost_ticks (updated in do_timer()) and the match reg value, so we

	 * lost_ticks(updated in do_timer()) and the match reg value is

	 * can use do_gettimeofday() from interrupt handlers.

	 * ensured, hence we can use do_gettimeofday() from interrupt

	 * handlers.

	 *

	 *

	 * HACK ALERT: it seems that the PXA timer regs aren't updated right

	 * HACK ALERT: it seems that the PXA timer regs aren't updated right

	 * away in all cases when a write occurs.  We therefore compare with

	 * away in all cases when a write occurs.  We therefore compare with

arch/arm/mach-sa1100/time.c

+8 −9
Original line number Original line Diff line number Diff line
@@ -70,15 +70,6 @@ static unsigned long sa1100_gettimeoffset (void) 
	return usec;

	return usec;

}

}





/*

 * We will be entered with IRQs enabled.

 *

 * Loop until we get ahead of the free running timer.

 * This ensures an exact clock tick count and time accuracy.

 * IRQs are disabled inside the loop to ensure coherence between

 * lost_ticks (updated in do_timer()) and the match reg value, so we

 * can use do_gettimeofday() from interrupt handlers.

 */

static irqreturn_t

static irqreturn_t

sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)

sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)

{

{
@@ -86,6 +77,14 @@ sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) 




	write_seqlock(&xtime_lock);

	write_seqlock(&xtime_lock);





	/*

	 * Loop until we get ahead of the free running timer.

	 * This ensures an exact clock tick count and time accuracy.

	 * Since IRQs are disabled at this point, coherence between

	 * lost_ticks(updated in do_timer()) and the match reg value is

	 * ensured, hence we can use do_gettimeofday() from interrupt

	 * handlers.

	 */

	do {

	do {

		timer_tick(regs);

		timer_tick(regs);

		OSSR = OSSR_M0;  /* Clear match on timer 0 */

		OSSR = OSSR_M0;  /* Clear match on timer 0 */