1 files changed, 9 insertions, 1 deletions

diff --git a/arch/x86/kernel/i8253.c b/arch/x86/kernel/i8253.c
index a42c80745325..0f8f35458a8f 100644
--- a/arch/x86/kernel/i8253.c
+++ b/arch/x86/kernel/i8253.c
@@ -197,7 +197,15 @@ static struct clocksource clocksource_pit = {
 
 static int __init init_pit_clocksource(void)
 {
-        if (num_possible_cpus() > 1) /* PIT does not scale! */
+         /*
+          * Several reasons not to register PIT as a clocksource:
+          *
+          * - On SMP PIT does not scale due to i8253_lock
+          * - when HPET is enabled
+          * - when local APIC timer is active (PIT is switched off)
+          */
+        if (num_possible_cpus() > 1 || is_hpet_enabled() ||
+            pit_clockevent.mode != CLOCK_EVT_MODE_PERIODIC)
                 return 0;
 
         clocksource_pit.mult = clocksource_hz2mult(CLOCK_TICK_RATE, 20);