From 2139cca802c8ade7571d78caef58475bac7771a7 Mon Sep 17 00:00:00 2001
From: Yasunori Goto <y-goto@jp.fujitsu.com>
Date: Thu, 2 Apr 2009 16:58:31 -0700
Subject: [PATCH] --- yaml --- r: 139706 b: refs/heads/master c:
 303d379c54fc9ed553562e36c1cbd1791a3f5d17 h: refs/heads/master v: v3

---
 [refs]                    |  2 +-
 trunk/drivers/char/hpet.c | 22 +++++++++++++++++++++-
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 5eff974e1615..67d3f41e48d2 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1f80769ffd36e74357fe896dc43dddf1af1510f3
+refs/heads/master: 303d379c54fc9ed553562e36c1cbd1791a3f5d17
diff --git a/trunk/drivers/char/hpet.c b/trunk/drivers/char/hpet.c
index 32b8bbf5003e..50dfa3bc71ce 100644
--- a/trunk/drivers/char/hpet.c
+++ b/trunk/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;