From: Ingo Molnar <mingo@elte.hu>
Date: Thu, 4 Sep 2008 20:47:47 +0000 (+0200)
Subject: x86: quick TSC calibration, improve
X-Git-Tag: v2.6.28-rc1~734^2^19~1
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=4156e9a8ef5b521185f451213d33fa661f38512e;p=linux-2.6-omap-h63xx.git

x86: quick TSC calibration, improve

- make sure the final TSC timestamp is reliable too

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 839070ba846..6dab90f6851 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -316,6 +316,12 @@ static unsigned long quick_pit_calibrate(void)
 		}
 		t2 = get_cycles();
 
+		/*
+		 * Make sure we can rely on the second TSC timestamp:
+		 */
+		if (!pit_expect_msb(--expect))
+			goto failed;
+
 		/*
 		 * Ok, if we get here, then we've seen the
 		 * MSB of the PIT decrement QUICK_PIT_ITERATIONS