* [PATCH] x86 tsc: Add the Intel Denverton Processor to native_calibrate_tsc()
@ 2017-01-21 7:52 Len Brown
2017-01-22 9:33 ` Ingo Molnar
0 siblings, 1 reply; 4+ messages in thread
From: Len Brown @ 2017-01-21 7:52 UTC (permalink / raw)
To: x86; +Cc: linux-kernel, Len Brown
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] x86 tsc: Add the Intel Denverton Processor to native_calibrate_tsc()
2017-01-21 7:52 [PATCH] x86 tsc: Add the Intel Denverton Processor to native_calibrate_tsc() Len Brown
@ 2017-01-22 9:33 ` Ingo Molnar
2017-01-23 18:49 ` Len Brown
0 siblings, 1 reply; 4+ messages in thread
From: Ingo Molnar @ 2017-01-22 9:33 UTC (permalink / raw)
To: Len Brown; +Cc: x86, linux-kernel, Len Brown, Thomas Gleixner
* Len Brown <lenb@kernel.org> wrote:
> 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:
Already upstream, as per:
695085b4bc76 x86/tsc: Add the Intel Denverton Processor to native_calibrate_tsc()
Thanks,
Ingo
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86 tsc: Add the Intel Denverton Processor to native_calibrate_tsc()
2017-01-22 9:33 ` Ingo Molnar
@ 2017-01-23 18:49 ` Len Brown
0 siblings, 0 replies; 4+ messages in thread
From: Len Brown @ 2017-01-23 18:49 UTC (permalink / raw)
To: Ingo Molnar; +Cc: X86 ML, linux-kernel, Len Brown, Thomas Gleixner
> Already upstream, as per:
>
> 695085b4bc76 x86/tsc: Add the Intel Denverton Processor to native_calibrate_tsc()
Thanks, Ingo,
Sorry for the repeat.
Len Brown, Intel Open Source Technology Center
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] x86 tsc: Add the Intel Denverton Processor to native_calibrate_tsc()
@ 2017-01-13 6:11 Len Brown
0 siblings, 0 replies; 4+ messages in thread
From: Len Brown @ 2017-01-13 6:11 UTC (permalink / raw)
To: x86; +Cc: linux-kernel, Len Brown
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2017-01-21 7:52 [PATCH] x86 tsc: Add the Intel Denverton Processor to native_calibrate_tsc() Len Brown
2017-01-22 9:33 ` Ingo Molnar
2017-01-23 18:49 ` Len Brown
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2017-01-13 6:11 Len Brown
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