4 files changed, 36 insertions, 27 deletions

diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
index 4d75b373f90..a0dcb7c87c3 100644
--- a/arch/i386/kernel/time.c
+++ b/arch/i386/kernel/time.c
@@ -441,7 +441,7 @@ static void __init hpet_time_init(void)
 	set_normalized_timespec(&wall_to_monotonic,
 		-xtime.tv_sec, -xtime.tv_nsec);
 
-	if (hpet_enable() >= 0) {
+	if ((hpet_enable() >= 0) && hpet_use_timer) {
 		printk("Using HPET for base-timer\n");
 	}
 
diff --git a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
index 244a31b04be..10a0cbb88e7 100644
--- a/arch/i386/kernel/time_hpet.c
+++ b/arch/i386/kernel/time_hpet.c
@@ -26,6 +26,7 @@
 static unsigned long hpet_period;	/* fsecs / HPET clock */
 unsigned long hpet_tick;		/* hpet clks count per tick */
 unsigned long hpet_address;		/* hpet memory map physical address */
+int hpet_use_timer;
 
 static int use_hpet; 		/* can be used for runtime check of hpet */
 static int boot_hpet_disable; 	/* boottime override for HPET timer */
@@ -73,27 +74,30 @@ static int hpet_timer_stop_set_go(unsigned long tick)
 	hpet_writel(0, HPET_COUNTER);
 	hpet_writel(0, HPET_COUNTER + 4);
 
-	/*
-	 * Set up timer 0, as periodic with first interrupt to happen at
-	 * hpet_tick, and period also hpet_tick.
-	 */
-	cfg = hpet_readl(HPET_T0_CFG);
-	cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
-	       HPET_TN_SETVAL | HPET_TN_32BIT;
-	hpet_writel(cfg, HPET_T0_CFG);
-
-	/*
-	 * The first write after writing TN_SETVAL to the config register sets
-	 * the counter value, the second write sets the threshold.
-	 */
-	hpet_writel(tick, HPET_T0_CMP);
-	hpet_writel(tick, HPET_T0_CMP);
+	if (hpet_use_timer) {
+		/*
+		 * Set up timer 0, as periodic with first interrupt to happen at
+		 * hpet_tick, and period also hpet_tick.
+		 */
+		cfg = hpet_readl(HPET_T0_CFG);
+		cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
+		       HPET_TN_SETVAL | HPET_TN_32BIT;
+		hpet_writel(cfg, HPET_T0_CFG);
 
+		/*
+		 * The first write after writing TN_SETVAL to the config register sets
+		 * the counter value, the second write sets the threshold.
+		 */
+		hpet_writel(tick, HPET_T0_CMP);
+		hpet_writel(tick, HPET_T0_CMP);
+	}
 	/*
  	 * Go!
  	 */
 	cfg = hpet_readl(HPET_CFG);
-	cfg |= HPET_CFG_ENABLE | HPET_CFG_LEGACY;
+	if (hpet_use_timer)
+		cfg |= HPET_CFG_LEGACY;
+	cfg |= HPET_CFG_ENABLE;
 	hpet_writel(cfg, HPET_CFG);
 
 	return 0;
@@ -128,12 +132,11 @@ int __init hpet_enable(void)
 	 * However, we can do with one timer otherwise using the
 	 * the single HPET timer for system time.
 	 */
-	if (
 #ifdef CONFIG_HPET_EMULATE_RTC
-		!(id & HPET_ID_NUMBER) ||
-#endif
-	    !(id & HPET_ID_LEGSUP))
+	if (!(id & HPET_ID_NUMBER))
 		return -1;
+#endif
+
 
 	hpet_period = hpet_readl(HPET_PERIOD);
 	if ((hpet_period < HPET_MIN_PERIOD) || (hpet_period > HPET_MAX_PERIOD))
@@ -152,6 +155,8 @@ int __init hpet_enable(void)
 	if (hpet_tick_rem > (hpet_period >> 1))
 		hpet_tick++; /* rounding the result */
 
+	hpet_use_timer = id & HPET_ID_LEGSUP;
+
 	if (hpet_timer_stop_set_go(hpet_tick))
 		return -1;
 
@@ -202,7 +207,8 @@ int __init hpet_enable(void)
 #endif
 
 #ifdef CONFIG_X86_LOCAL_APIC
-	wait_timer_tick = wait_hpet_tick;
+	if (hpet_use_timer)
+		wait_timer_tick = wait_hpet_tick;
 #endif
 	return 0;
 }
diff --git a/arch/i386/kernel/timers/timer_hpet.c b/arch/i386/kernel/timers/timer_hpet.c
index 713134e7184..f778f471a09 100644
--- a/arch/i386/kernel/timers/timer_hpet.c
+++ b/arch/i386/kernel/timers/timer_hpet.c
@@ -79,7 +79,7 @@ static unsigned long get_offset_hpet(void)
 
 	eax = hpet_readl(HPET_COUNTER);
 	eax -= hpet_last;	/* hpet delta */
-
+	eax = min(hpet_tick, eax);
 	/*
          * Time offset = (hpet delta) * ( usecs per HPET clock )
 	 *             = (hpet delta) * ( usecs per tick / HPET clocks per tick)
@@ -105,9 +105,12 @@ static void mark_offset_hpet(void)
 	last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
 	rdtsc(last_tsc_low, last_tsc_high);
 
-	offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
-	if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))) {
-		int lost_ticks = (offset - hpet_last) / hpet_tick;
+	if (hpet_use_timer)
+		offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
+	else
+		offset = hpet_readl(HPET_COUNTER);
+	if (unlikely(((offset - hpet_last) >= (2*hpet_tick)) && (hpet_last != 0))) {
+		int lost_ticks = ((offset - hpet_last) / hpet_tick) - 1;
 		jiffies_64 += lost_ticks;
 	}
 	hpet_last = offset;
diff --git a/arch/i386/kernel/timers/timer_tsc.c b/arch/i386/kernel/timers/timer_tsc.c
index a685994e5c8..7926d967be0 100644
--- a/arch/i386/kernel/timers/timer_tsc.c
+++ b/arch/i386/kernel/timers/timer_tsc.c
@@ -477,7 +477,7 @@ static int __init init_tsc(char* override)
 	if (cpu_has_tsc) {
 		unsigned long tsc_quotient;
 #ifdef CONFIG_HPET_TIMER
-		if (is_hpet_enabled()){
+		if (is_hpet_enabled() && hpet_use_timer) {
 			unsigned long result, remain;
 			printk("Using TSC for gettimeofday\n");
 			tsc_quotient = calibrate_tsc_hpet(NULL);