lkml.org 
[lkml]   [2017]   [Jan]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] x86 tsc: Add the Intel Denverton Processor to native_calibrate_tsc()
Date
From: Len Brown <len.brown@intel.com>

The Intel Denverton microserver uses a 25 MHz TSC crystal,
so we can derive its exact * TSC frequency
using CPUID and some arithmetic, eg.

TSC: 1800 MHz (25000000 Hz * 216 / 3 / 1000000)

* 'exact' is only as good as the crystal, which should be +/- 20ppm

Signed-off-by: Len Brown <len.brown@intel.com>
---
arch/x86/kernel/tsc.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 46b2f41f8b05..b3e397a0f29d 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -694,6 +694,7 @@ unsigned long native_calibrate_tsc(void)
crystal_khz = 24000; /* 24.0 MHz */
break;
case INTEL_FAM6_SKYLAKE_X:
+ case INTEL_FAM6_ATOM_DENVERTON:
crystal_khz = 25000; /* 25.0 MHz */
break;
case INTEL_FAM6_ATOM_GOLDMONT:
--
2.11.0.161.g6610af872
\
 
 \ /
  Last update: 2017-01-21 08:54    [W:0.069 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site