linux-kernel - [PATCH 2/2] x86/tsc: Add additional Intel CPU models to crystal

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Date:   Thu, 15 Sep 2016 11:04:18 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Prarit Bhargava <prarit@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Rafael Aquini <aquini@...hat.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Len Brown <len.brown@...el.com>, lenb@...nel.org
Subject: [PATCH 2/2] x86/tsc: Add additional Intel CPU models to crystal_khz whitelist

In commit aa297292d708 ("x86/tsc: Enumerate SKL cpu_khz and tsc_khz via
CPUID"), the kernel added support for Intel processors which had
a different CPU base-frequency and TSC frequency.

The turbostat utility has been updated with KBL and SKX processors,
and they should also be added to the crystal_khz white list.

For example, on INTEL_FAM6_KABYLAKE_MOBILE native_calibrate_tsc() returns 0 MHz
for tsc_khz and after this patch native_calibrate_tsc() returns 1608 MHz.

Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: Rafael Aquini <aquini@...hat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Len Brown <len.brown@...el.com>
Cc: lenb@...nel.org
---
 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 2344758ba8a3..dfa70a8867dc 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -689,11 +689,18 @@ unsigned long native_calibrate_tsc(void)
 		switch (boot_cpu_data.x86_model) {
 		case INTEL_FAM6_SKYLAKE_MOBILE:
 		case INTEL_FAM6_SKYLAKE_DESKTOP:
+		case INTEL_FAM6_KABYLAKE_MOBILE:
+		case INTEL_FAM6_KABYLAKE_DESKTOP:
 			crystal_khz = 24000;	/* 24.0 MHz */
 			break;
+		case INTEL_FAM6_SKYLAKE_X:
+			crystal_khz = 24000;	/* 25.0 MHz */
+			break;
 		case INTEL_FAM6_ATOM_GOLDMONT:
 			crystal_khz = 19200;	/* 19.2 MHz */
 			break;
+		default:
+			crystal_khz = 0;
 		}
 	}
 
-- 
1.7.9.3