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Diffstat (limited to 'arch/i386/kernel/time_hpet.c')
-rw-r--r--arch/i386/kernel/time_hpet.c37
1 files changed, 31 insertions, 6 deletions
diff --git a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
index 14a1376fedd..6bf14a4e995 100644
--- a/arch/i386/kernel/time_hpet.c
+++ b/arch/i386/kernel/time_hpet.c
@@ -301,23 +301,25 @@ int hpet_rtc_timer_init(void)
hpet_rtc_int_freq = DEFAULT_RTC_INT_FREQ;
local_irq_save(flags);
+
cnt = hpet_readl(HPET_COUNTER);
cnt += ((hpet_tick*HZ)/hpet_rtc_int_freq);
hpet_writel(cnt, HPET_T1_CMP);
hpet_t1_cmp = cnt;
- local_irq_restore(flags);
cfg = hpet_readl(HPET_T1_CFG);
cfg &= ~HPET_TN_PERIODIC;
cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
hpet_writel(cfg, HPET_T1_CFG);
+ local_irq_restore(flags);
+
return 1;
}
static void hpet_rtc_timer_reinit(void)
{
- unsigned int cfg, cnt;
+ unsigned int cfg, cnt, ticks_per_int, lost_ints;
if (unlikely(!(PIE_on | AIE_on | UIE_on))) {
cfg = hpet_readl(HPET_T1_CFG);
@@ -332,10 +334,33 @@ static void hpet_rtc_timer_reinit(void)
hpet_rtc_int_freq = DEFAULT_RTC_INT_FREQ;
/* It is more accurate to use the comparator value than current count.*/
- cnt = hpet_t1_cmp;
- cnt += hpet_tick*HZ/hpet_rtc_int_freq;
- hpet_writel(cnt, HPET_T1_CMP);
- hpet_t1_cmp = cnt;
+ ticks_per_int = hpet_tick * HZ / hpet_rtc_int_freq;
+ hpet_t1_cmp += ticks_per_int;
+ hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
+
+ /*
+ * If the interrupt handler was delayed too long, the write above tries
+ * to schedule the next interrupt in the past and the hardware would
+ * not interrupt until the counter had wrapped around.
+ * So we have to check that the comparator wasn't set to a past time.
+ */
+ cnt = hpet_readl(HPET_COUNTER);
+ if (unlikely((int)(cnt - hpet_t1_cmp) > 0)) {
+ lost_ints = (cnt - hpet_t1_cmp) / ticks_per_int + 1;
+ /* Make sure that, even with the time needed to execute
+ * this code, the next scheduled interrupt has been moved
+ * back to the future: */
+ lost_ints++;
+
+ hpet_t1_cmp += lost_ints * ticks_per_int;
+ hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
+
+ if (PIE_on)
+ PIE_count += lost_ints;
+
+ printk(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n",
+ hpet_rtc_int_freq);
+ }
}
/*