linux-kernel - [PATCH 3/4] x86/tsc: mark Intel ATOM

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Date:   Tue, 15 Nov 2016 12:27:23 -0800
From:   Bin Gao <bin.gao@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
        x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, Bin Gao <bin.gao@...el.com>
Subject: [PATCH 3/4] x86/tsc: mark Intel ATOM_GOLDMONT TSC reliable

On Intel GOLDMONT Atom SoC TSC is the only reliable clocksource.
We mark TSC reliable to avoid watchdog on it.

Signed-off-by: Bin Gao <bin.gao@...el.com>
---
 arch/x86/kernel/tsc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index f1a7fb5..354b302 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -709,6 +709,13 @@ unsigned long native_calibrate_tsc(void)
 	 */
 	setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
 
+	/*
+	 * For Atom SoCs TSC is the only reliable clocksource.
+	 * Mark TSC reliable so no watchdog on it.
+	 */
+	if (boot_cpu_data.x86_model == INTEL_FAM6_ATOM_GOLDMONT)
+		setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
+
 	return crystal_khz * ebx_numerator / eax_denominator;
 }
 
-- 
1.9.1