Commit-ID: e9cdd343a5e42c43bcda01e609fa23089e026470 Gitweb: http://git.kernel.org/tip/e9cdd343a5e42c43bcda01e609fa23089e026470 Author: Boris Ostrovsky <ostr@xxxxxxxxx> AuthorDate: Thu, 26 May 2011 11:19:52 -0400 Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> CommitDate: Thu, 26 May 2011 10:38:30 -0700 x86, amd: Do not enable ARAT feature on AMD processors below family 0x12 Commit b87cf80af3ba4b4c008b4face3c68d604e1715c6 added support for ARAT (Always Running APIC timer) on AMD processors that are not affected by erratum 400. This erratum is present on certain processor families and prevents APIC timer from waking up the CPU when it is in a deep C state, including C1E state. Determining whether a processor is affected by this erratum may have some corner cases and handling these cases is somewhat complicated. In the interest of simplicity we won't claim ARAT support on processor families below 0x12 and will go back to broadcasting timer when going idle. Signed-off-by: Boris Ostrovsky <ostr@xxxxxxxxx> Link: http://lkml.kernel.org/r/1306423192-19774-1-git-send-email-ostr@xxxxxxxxx Tested-by: Boris Petkov <borislav.petkov@xxxxxxx> Cc: Hans Rosenfeld <Hans.Rosenfeld@xxxxxxx> Cc: Andreas Herrmann <Andreas.Herrmann3@xxxxxxx> Cc: Chuck Ebbert <cebbert@xxxxxxxxxx> Cc: stable@xxxxxxxxxx # 32.x, 38.x, 39.x Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> --- arch/x86/kernel/cpu/amd.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 8f5cabb..b13ed39 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -612,8 +612,11 @@ 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)) + /* + * Family 0x12 and above processors have APIC timer + * running in deep C states. + */ + if (c->x86 > 0x11) set_cpu_cap(c, X86_FEATURE_ARAT); /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html