2 files changed, 8 insertions, 2 deletions

diff --git a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
index cb1f313858e..9caeaa315cd 100644
--- a/arch/i386/kernel/time_hpet.c
+++ b/arch/i386/kernel/time_hpet.c
@@ -275,6 +275,7 @@ static unsigned long PIE_freq = DEFAULT_RTC_INT_FREQ;
 static unsigned long PIE_count;
 
 static unsigned long hpet_rtc_int_freq; /* RTC interrupt frequency */
+static unsigned int hpet_t1_cmp; /* cached comparator register */
 
 /*
  * Timer 1 for RTC, we do not use periodic interrupt feature,
@@ -306,6 +307,7 @@ int hpet_rtc_timer_init(void)
         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);
@@ -333,9 +335,10 @@ 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_readl(HPET_T1_CMP);
+        cnt = hpet_t1_cmp;
         cnt += hpet_tick*HZ/hpet_rtc_int_freq;
         hpet_writel(cnt, HPET_T1_CMP);
+        hpet_t1_cmp = cnt;
 }
 
 /*
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 35a896ef4c3..fdaddc4e528 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -1089,6 +1089,7 @@ static unsigned long PIE_freq = DEFAULT_RTC_INT_FREQ;
 static unsigned long PIE_count;
 
 static unsigned long hpet_rtc_int_freq; /* RTC interrupt frequency */
+static unsigned int hpet_t1_cmp; /* cached comparator register */
 
 int is_hpet_enabled(void)
 {
@@ -1125,6 +1126,7 @@ int hpet_rtc_timer_init(void)
         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);
@@ -1152,9 +1154,10 @@ 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_readl(HPET_T1_CMP);
+        cnt = hpet_t1_cmp;
         cnt += hpet_tick*HZ/hpet_rtc_int_freq;
         hpet_writel(cnt, HPET_T1_CMP);
+        hpet_t1_cmp = cnt;
 }
 
 /*