1 files changed, 21 insertions, 1 deletions

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 32b8bbf5003e..50dfa3bc71ce 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -713,7 +713,7 @@ static struct ctl_table_header *sysctl_header;
  */
 #define TICK_CALIBRATE  (1000UL)
 
-static unsigned long hpet_calibrate(struct hpets *hpetp)
+static unsigned long __hpet_calibrate(struct hpets *hpetp)
 {
         struct hpet_timer __iomem *timer = NULL;
         unsigned long t, m, count, i, flags, start;
@@ -750,6 +750,26 @@ static unsigned long hpet_calibrate(struct hpets *hpetp)
         return (m - start) / i;
 }
 
+static unsigned long hpet_calibrate(struct hpets *hpetp)
+{
+        unsigned long ret = -1;
+        unsigned long tmp;
+
+        /*
+         * Try to calibrate until return value becomes stable small value.
+         * If SMI interruption occurs in calibration loop, the return value
+         * will be big. This avoids its impact.
+         */
+        for ( ; ; ) {
+                tmp = __hpet_calibrate(hpetp);
+                if (ret <= tmp)
+                        break;
+                ret = tmp;
+        }
+
+        return ret;
+}
+
 int hpet_alloc(struct hpet_data *hdp)
 {
         u64 cap, mcfg;