From af43aa1191dd7abcfece56b712966bb19df94653 Mon Sep 17 00:00:00 2001 From: Paul Menzel Date: Wed, 23 Jan 2019 00:24:37 +0100 Subject: [PATCH] x86/kernel/tsc: Debug early TSC calibration Signed-off-by: Paul Menzel --- arch/x86/kernel/tsc.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index e9f777bfed40..28d0b4b29668 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -549,8 +549,10 @@ static unsigned long quick_pit_calibrate(void) if (pit_expect_msb(0xff, &tsc, &d1)) { for (i = 1; i <= MAX_QUICK_PIT_ITERATIONS; i++) { - if (!pit_expect_msb(0xff-i, &delta, &d2)) + if (!pit_expect_msb(0xff-i, &delta, &d2)) { + pr_err("%s: break in if !pit_expect_msb, i = %d\n", __func__, i); break; + } delta -= tsc; @@ -575,12 +577,14 @@ static unsigned long quick_pit_calibrate(void) * This also guarantees serialization of the * last cycle read ('d2') in pit_expect_msb. */ - if (!pit_verify_msb(0xfe - i)) + if (!pit_verify_msb(0xfe - i)) { + pr_err("%s: break in if !pit_verify_msb\n", __func__); break; + } goto success; } } - pr_info("Fast TSC calibration failed\n"); + pr_info("Fast TSC calibration failed, i = %d\n", i); return 0; success: -- 2.20.1