Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[pandora-kernel.git] / kernel / time / timekeeping.c

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 342408c..2b021b0 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -604,6 +604,12 @@ static struct timespec timekeeping_suspend_time;
  */
 static void __timekeeping_inject_sleeptime(struct timespec *delta)
 {
+       if (!timespec_valid(delta)) {
+               printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
+                                       "sleep delta value!\n");
+               return;
+       }
+
        xtime = timespec_add(xtime, *delta);
        wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta);
        total_sleep_time = timespec_add(total_sleep_time, *delta);
@@ -686,12 +692,34 @@ static void timekeeping_resume(void)
 static int timekeeping_suspend(void)
 {
        unsigned long flags;
+       struct timespec         delta, delta_delta;
+       static struct timespec  old_delta;
 
        read_persistent_clock(&timekeeping_suspend_time);
 
        write_seqlock_irqsave(&xtime_lock, flags);
        timekeeping_forward_now();
        timekeeping_suspended = 1;
+
+       /*
+        * To avoid drift caused by repeated suspend/resumes,
+        * which each can add ~1 second drift error,
+        * try to compensate so the difference in system time
+        * and persistent_clock time stays close to constant.
+        */
+       delta = timespec_sub(xtime, timekeeping_suspend_time);
+       delta_delta = timespec_sub(delta, old_delta);
+       if (abs(delta_delta.tv_sec)  >= 2) {
+               /*
+                * if delta_delta is too large, assume time correction
+                * has occured and set old_delta to the current delta.
+                */
+               old_delta = delta;
+       } else {
+               /* Otherwise try to adjust old_system to compensate */
+               timekeeping_suspend_time =
+                       timespec_add(timekeeping_suspend_time, delta_delta);
+       }
        write_sequnlock_irqrestore(&xtime_lock, flags);
 
        clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);