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authorBoris Ostrovsky <boris.ostrovsky@amd.com>2011-03-15 12:13:44 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2011-04-21 14:32:46 -0700
commitd7b7f0c401303dd7eafcff11752fe74d3b75c766 (patch)
treee3543593717514e5db398fac3e3420cd08ec5e0f /arch
parent78caa50ce2c5d8ccf9547978aa74e1ba5de08b00 (diff)
downloadlinux-2.6.38-lt-ux500-d7b7f0c401303dd7eafcff11752fe74d3b75c766.tar.gz
x86, AMD: Set ARAT feature on AMD processors
commit b87cf80af3ba4b4c008b4face3c68d604e1715c6 upstream. Support for Always Running APIC timer (ARAT) was introduced in commit db954b5898dd3ef3ef93f4144158ea8f97deb058. This feature allows us to avoid switching timers from LAPIC to something else (e.g. HPET) and go into timer broadcasts when entering deep C-states. AMD processors don't provide a CPUID bit for that feature but they also keep APIC timers running in deep C-states (except for cases when the processor is affected by erratum 400). Therefore we should set ARAT feature bit on AMD CPUs. Tested-by: Borislav Petkov <borislav.petkov@amd.com> Acked-by: Andreas Herrmann <andreas.herrmann3@amd.com> Acked-by: Mark Langsdorf <mark.langsdorf@amd.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@amd.com> LKML-Reference: <1300205624-4813-1-git-send-email-ostr@amd64.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/amd.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 7c7bedb83c5..48eaa1b6fc4 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -594,6 +594,10 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
}
}
#endif
+
+ /* As a rule processors have APIC timer running in deep C states */
+ if (c->x86 >= 0xf && !cpu_has_amd_erratum(amd_erratum_400))
+ set_cpu_cap(c, X86_FEATURE_ARAT);
}
#ifdef CONFIG_X86_32