[PATCH] timer TSC check suspend notifier change

[firefly-linux-kernel-4.4.55.git] / arch / i386 / kernel / timers / timer_tsc.c

diff --git a/arch/i386/kernel/timers/timer_tsc.c b/arch/i386/kernel/timers/timer_tsc.c
index 47675bbbb316eedb7edd0ba6a0bd7982d8d982a0..f1187ddb0d0fc07809a3f5f20ab43177b6fbe61f 100644 (file)
--- a/arch/i386/kernel/timers/timer_tsc.c
+++ b/arch/i386/kernel/timers/timer_tsc.c
@@ -45,6 +45,15 @@ static unsigned long last_tsc_high; /* msb 32 bits of Time Stamp Counter */
 static unsigned long long monotonic_base;
 static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;
 
+/* Avoid compensating for lost ticks before TSCs are synched */
+static int detect_lost_ticks;
+static int __init start_lost_tick_compensation(void)
+{
+       detect_lost_ticks = 1;
+       return 0;
+}
+late_initcall(start_lost_tick_compensation);
+
 /* convert from cycles(64bits) => nanoseconds (64bits)
  *  basic equation:
  *             ns = cycles / (freq / ns_per_sec)
@@ -65,7 +74,7 @@ static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;
  *
  *                     -johnstul@us.ibm.com "math is hard, lets go shopping!"
  */
-static unsigned long cyc2ns_scale; 
+static unsigned long cyc2ns_scale __read_mostly;
 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
 
 static inline void set_cyc2ns_scale(unsigned long cpu_khz)
@@ -196,7 +205,8 @@ static void mark_offset_tsc_hpet(void)
 
        /* lost tick compensation */
        offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
-       if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))) {
+       if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))
+                                       && detect_lost_ticks) {
                int lost_ticks = (offset - hpet_last) / hpet_tick;
                jiffies_64 += lost_ticks;
        }
@@ -269,9 +279,13 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 {
        struct cpufreq_freqs *freq = data;
 
-       if (val != CPUFREQ_RESUMECHANGE)
+       if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
                write_seqlock_irq(&xtime_lock);
        if (!ref_freq) {
+               if (!freq->old){
+                       ref_freq = freq->new;
+                       goto end;
+               }
                ref_freq = freq->old;
                loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy;
 #ifndef CONFIG_SMP
@@ -297,7 +311,8 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 #endif
        }
 
-       if (val != CPUFREQ_RESUMECHANGE)
+end:
+       if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
                write_sequnlock_irq(&xtime_lock);
 
        return 0;
@@ -421,7 +436,7 @@ static void mark_offset_tsc(void)
        delta += delay_at_last_interrupt;
        lost = delta/(1000000/HZ);
        delay = delta%(1000000/HZ);
-       if (lost >= 2) {
+       if (lost >= 2 && detect_lost_ticks) {
                jiffies_64 += lost-1;
 
                /* sanity check to ensure we're not always losing ticks */