From 4156e9a8ef5b521185f451213d33fa661f38512e Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 4 Sep 2008 22:47:47 +0200 Subject: [PATCH] x86: quick TSC calibration, improve - make sure the final TSC timestamp is reliable too Signed-off-by: Ingo Molnar --- arch/x86/kernel/tsc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 839070ba8465..6dab90f68515 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 -- 2.39.2