1 files changed, 24 insertions, 12 deletions

diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index d269a8f3329c..446aced33aff 100644
--- a/drivers/acpi/acpi_pad.c
+++ b/drivers/acpi/acpi_pad.c
@@ -46,6 +46,8 @@ static unsigned long power_saving_mwait_eax;
 
 static unsigned char tsc_detected_unstable;
 static unsigned char tsc_marked_unstable;
+static unsigned char lapic_detected_unstable;
+static unsigned char lapic_marked_unstable;
 
 static void power_saving_mwait_init(void)
 {
@@ -75,9 +77,6 @@ static void power_saving_mwait_init(void)
         power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
                 (highest_subcstate - 1);
 
-        for_each_online_cpu(i)
-                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &i);
-
 #if defined(CONFIG_GENERIC_TIME) && defined(CONFIG_X86)
         switch (boot_cpu_data.x86_vendor) {
         case X86_VENDOR_AMD:
@@ -86,13 +85,15 @@ static void power_saving_mwait_init(void)
                  * AMD Fam10h TSC will tick in all
                  * C/P/S0/S1 states when this bit is set.
                  */
-                if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
-                        return;
-
-                /*FALL THROUGH*/
+                if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
+                        tsc_detected_unstable = 1;
+                if (!boot_cpu_has(X86_FEATURE_ARAT))
+                        lapic_detected_unstable = 1;
+                break;
         default:
-                /* TSC could halt in idle */
+                /* TSC & LAPIC could halt in idle */
                 tsc_detected_unstable = 1;
+                lapic_detected_unstable = 1;
         }
 #endif
 }
@@ -180,10 +181,20 @@ static int power_saving_thread(void *data)
                                 mark_tsc_unstable("TSC halts in idle");
                                 tsc_marked_unstable = 1;
                         }
+                        if (lapic_detected_unstable && !lapic_marked_unstable) {
+                                int i;
+                                /* LAPIC could halt in idle, so notify users */
+                                for_each_online_cpu(i)
+                                        clockevents_notify(
+                                                CLOCK_EVT_NOTIFY_BROADCAST_ON,
+                                                &i);
+                                lapic_marked_unstable = 1;
+                        }
                         local_irq_disable();
                         cpu = smp_processor_id();
-                        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
-                                &cpu);
+                        if (lapic_marked_unstable)
+                                clockevents_notify(
+                                        CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
                         stop_critical_timings();
 
                         __monitor((void *)&current_thread_info()->flags, 0, 0);
@@ -192,8 +203,9 @@ static int power_saving_thread(void *data)
                                 __mwait(power_saving_mwait_eax, 1);
 
                         start_critical_timings();
-                        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
-                                &cpu);
+                        if (lapic_marked_unstable)
+                                clockevents_notify(
+                                        CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
                         local_irq_enable();
 
                         if (jiffies > expire_time) {