Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6

[powerpc.git] / arch / x86_64 / kernel / time.c

diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 9dd15d1..1c255ee 100644 (file)
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -1164,23 +1164,25 @@ 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);
@@ -1195,10 +1197,33 @@ 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);
+       }
 }
 
 /*