From 4b034417c99d59209ecdffb7f648868602e286c2 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sat, 21 Jul 2007 17:11:12 +0200
Subject: [PATCH] --- yaml --- r: 62425 b: refs/heads/master c:
 075bcd1f9726b8a1caff86eda06f29f71fb21235 h: refs/heads/master i:   62423:
 62fe6775d986ec480802ee2b82439ddb301f6f8d v: v3

---
 [refs]                        |  2 +-
 trunk/arch/i386/kernel/hpet.c | 24 +++++++++++++++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 12ae29571f35..de9f95ae7442 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: df2edcf3b6ba54d9ffa620e322583cd994a6e54a
+refs/heads/master: 075bcd1f9726b8a1caff86eda06f29f71fb21235
diff --git a/trunk/arch/i386/kernel/hpet.c b/trunk/arch/i386/kernel/hpet.c
index 662d7976a9ea..b93310d11950 100644
--- a/trunk/arch/i386/kernel/hpet.c
+++ b/trunk/arch/i386/kernel/hpet.c
@@ -232,7 +232,8 @@ int __init hpet_enable(void)
 {
 	unsigned long id;
 	uint64_t hpet_freq;
-	u64 tmp;
+	u64 tmp, start, now;
+	cycle_t t1;
 
 	if (!is_hpet_capable())
 		return 0;
@@ -279,6 +280,27 @@ int __init hpet_enable(void)
 	/* Start the counter */
 	hpet_start_counter();
 
+	/* Verify whether hpet counter works */
+	t1 = read_hpet();
+	rdtscll(start);
+
+	/*
+	 * We don't know the TSC frequency yet, but waiting for
+	 * 200000 TSC cycles is safe:
+	 * 4 GHz == 50us
+	 * 1 GHz == 200us
+	 */
+	do {
+		rep_nop();
+		rdtscll(now);
+	} while ((now - start) < 200000UL);
+
+	if (t1 == read_hpet()) {
+		printk(KERN_WARNING
+		       "HPET counter not counting. HPET disabled\n");
+		goto out_nohpet;
+	}
+
 	/* Initialize and register HPET clocksource
 	 *
 	 * hpet period is in femto seconds per cycle