1 files changed, 47 insertions, 34 deletions

diff --git a/arch/x86/kernel/apic.c b/arch/x86/kernel/apic.c
index d730e8d31727..784116933c70 100644
--- a/arch/x86/kernel/apic.c
+++ b/arch/x86/kernel/apic.c
@@ -538,14 +538,51 @@ static void __init lapic_cal_handler(struct clock_event_device *dev)
         }
 }
 
+static int __init calibrate_by_pmtimer(long deltapm, long *delta)
+{
+        const long pm_100ms = PMTMR_TICKS_PER_SEC / 10;
+        const long pm_thresh = pm_100ms / 100;
+        unsigned long mult;
+        u64 res;
+
+#ifndef CONFIG_X86_PM_TIMER
+        return -1;
+#endif
+
+        apic_printk(APIC_VERBOSE, "... PM timer delta = %ld\n", deltapm);
+
+        /* Check, if the PM timer is available */
+        if (!deltapm)
+                return -1;
+
+        mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC, 22);
+
+        if (deltapm > (pm_100ms - pm_thresh) &&
+            deltapm < (pm_100ms + pm_thresh)) {
+                apic_printk(APIC_VERBOSE, "... PM timer result ok\n");
+        } else {
+                res = (((u64)deltapm) *  mult) >> 22;
+                do_div(res, 1000000);
+                printk(KERN_WARNING "APIC calibration not consistent "
+                        "with PM Timer: %ldms instead of 100ms\n",
+                        (long)res);
+                /* Correct the lapic counter value */
+                res = (((u64)(*delta)) * pm_100ms);
+                do_div(res, deltapm);
+                printk(KERN_INFO "APIC delta adjusted to PM-Timer: "
+                        "%lu (%ld)\n", (unsigned long)res, *delta);
+                *delta = (long)res;
+        }
+
+        return 0;
+}
+
 static int __init calibrate_APIC_clock(void)
 {
         struct clock_event_device *levt = &__get_cpu_var(lapic_events);
-        const long pm_100ms = PMTMR_TICKS_PER_SEC/10;
-        const long pm_thresh = pm_100ms/100;
         void (*real_handler)(struct clock_event_device *dev);
         unsigned long deltaj;
-        long delta, deltapm;
+        long delta;
         int pm_referenced = 0;
 
         local_irq_disable();
@@ -575,36 +612,9 @@ static int __init calibrate_APIC_clock(void)
         delta = lapic_cal_t1 - lapic_cal_t2;
         apic_printk(APIC_VERBOSE, "... lapic delta = %ld\n", delta);
 
-#ifdef CONFIG_X86_PM_TIMER
-        /* Check, if the PM timer is available */
-        deltapm = lapic_cal_pm2 - lapic_cal_pm1;
-        apic_printk(APIC_VERBOSE, "... PM timer delta = %ld\n", deltapm);
-
-        if (deltapm) {
-                unsigned long mult;
-                u64 res;
-
-                mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC, 22);
-
-                if (deltapm > (pm_100ms - pm_thresh) &&
-                    deltapm < (pm_100ms + pm_thresh)) {
-                        apic_printk(APIC_VERBOSE, "... PM timer result ok\n");
-                } else {
-                        res = (((u64) deltapm) *  mult) >> 22;
-                        do_div(res, 1000000);
-                        printk(KERN_WARNING "APIC calibration not consistent "
-                               "with PM Timer: %ldms instead of 100ms\n",
-                               (long)res);
-                        /* Correct the lapic counter value */
-                        res = (((u64) delta) * pm_100ms);
-                        do_div(res, deltapm);
-                        printk(KERN_INFO "APIC delta adjusted to PM-Timer: "
-                               "%lu (%ld)\n", (unsigned long) res, delta);
-                        delta = (long) res;
-                }
-                pm_referenced = 1;
-        }
-#endif
+        /* we trust the PM based calibration if possible */
+        pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,
+                                        &delta);
 
         /* Calculate the scaled math multiplication factor */
         lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
@@ -646,7 +656,10 @@ static int __init calibrate_APIC_clock(void)
 
         levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
 
-        /* We trust the pm timer based calibration */
+        /*
+         * PM timer calibration failed or not turned on
+         * so lets try APIC timer based calibration
+         */
         if (!pm_referenced) {
                 apic_printk(APIC_VERBOSE, "... verify APIC timer\n");