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| author | Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> | 2009-04-06 18:51:29 -0700 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2009-04-07 18:17:51 -0400 |
| commit | db954b5898dd3ef3ef93f4144158ea8f97deb058 (patch) | |
| tree | 781b62baa5aa262fca99198ba326e5e9cc44b26a /drivers/acpi | |
| parent | 577c9c456f0e1371cbade38eaf91ae8e8a308555 (diff) | |
| download | linux-db954b5898dd3ef3ef93f4144158ea8f97deb058.tar.bz2 | |
x86 ACPI: Add support for Always Running APIC timer
Add support for Always Running APIC timer, CPUID_0x6_EAX_Bit2.
This bit means the APIC timer continues to run even when CPU is
in deep C-states.
The advantage is that we can use LAPIC timer on these CPUs
always, and there is no need for "slow to read and program"
external timers (HPET/PIT) and the timer broadcast logic
and related code in C-state entry and exit.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi')
| -rw-r--r-- | drivers/acpi/processor_idle.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 4e6e758bd397..6fe121434ffb 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -145,6 +145,9 @@ static void acpi_timer_check_state(int state, struct acpi_processor *pr, struct acpi_processor_power *pwr = &pr->power; u8 type = local_apic_timer_c2_ok ? ACPI_STATE_C3 : ACPI_STATE_C2; + if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT)) + return; + /* * Check, if one of the previous states already marked the lapic * unstable |