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Patch "x86/tsc: Add the Intel Denverton Processor to native_calibrate_tsc()" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jul 3, 2017

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This is a note to let you know that I've just added the patch titled

x86/tsc: Add the Intel Denverton Processor to native_calibrate_tsc()

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-tsc-add-the-intel-denverton-processor-to-native_calibrate_tsc.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From foo@baz Mon Jul 3 13:33:55 CEST 2017

From: Len Brown <[email protected]>
Date: Fri, 13 Jan 2017 01:11:18 -0500
Subject: x86/tsc: Add the Intel Denverton Processor to native_calibrate_tsc()

From: Len Brown <[email protected]>

[ Upstream commit 695085b4bc7603551db0b3da897b8bf9893ca218 ]

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

---
 arch/x86/kernel/tsc.c |    1 +
 1 file changed, 1 insertion(+)
arch/x86/kernel/tsc.c +1 -0
@@ -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:

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/x86-tsc-add-the-intel-denverton-processor-to-native_calibrate_tsc.patch