From db954b5898dd3ef3ef93f4144158ea8f97deb058 Mon Sep 17 00:00:00 2001 From: Venkatesh Pallipadi Date: Mon, 6 Apr 2009 18:51:29 -0700 Subject: 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 Acked-by: H. Peter Anvin Signed-off-by: Len Brown --- drivers/acpi/processor_idle.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers') diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 4e6e758bd39..6fe121434ff 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 -- cgit v1.2.3