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[ARM] 2863/1: clarify comment in PXA2xx and SA1x00 timer code

Patch from Nicolas Pitre

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Nicolas Pitre 20 年之前
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共有 2 个文件被更改,包括 12 次插入12 次删除
  1. 4 3
      arch/arm/mach-pxa/time.c
  2. 8 9
      arch/arm/mach-sa1100/time.c

+ 4 - 3
arch/arm/mach-pxa/time.c

@@ -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.
 	 * 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.
+	 * 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.
 	 *
 	 * 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

+ 8 - 9
arch/arm/mach-sa1100/time.c

@@ -70,15 +70,6 @@ static unsigned long sa1100_gettimeoffset (void)
 	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
 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);
 
+	/*
+	 * 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 {
 		timer_tick(regs);
 		OSSR = OSSR_M0;  /* Clear match on timer 0 */