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authorBoris Ostrovsky <ostr@amd64.org>2011-05-26 11:19:52 -0400
committerH. Peter Anvin <hpa@linux.intel.com>2011-05-26 13:38:30 -0400
commite9cdd343a5e42c43bcda01e609fa23089e026470 (patch)
treecc814236d5dfc6c8555c3c630a493a85d23fbd93 /arch/x86
parentb80ef10e84d85a06bcd0b3a24a752ec32d0e0e40 (diff)
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@amd64.org> Link: http://lkml.kernel.org/r/1306423192-19774-1-git-send-email-ostr@amd64.org Tested-by: Boris Petkov <borislav.petkov@amd.com> Cc: Hans Rosenfeld <Hans.Rosenfeld@amd.com> Cc: Andreas Herrmann <Andreas.Herrmann3@amd.com> Cc: Chuck Ebbert <cebbert@redhat.com> Cc: stable@kernel.org # 32.x, 38.x, 39.x Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/amd.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 8f5cabb3c5b0..b13ed393dfce 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)
612 } 612 }
613#endif 613#endif
614 614
615 /* As a rule processors have APIC timer running in deep C states */ 615 /*
616 if (c->x86 > 0xf && !cpu_has_amd_erratum(amd_erratum_400)) 616 * Family 0x12 and above processors have APIC timer
617 * running in deep C states.
618 */
619 if (c->x86 > 0x11)
617 set_cpu_cap(c, X86_FEATURE_ARAT); 620 set_cpu_cap(c, X86_FEATURE_ARAT);
618 621
619 /* 622 /*