[PATCH] i386: Handle missing local APIC timer interrupts on C3 state

Whenever we see that a CPU is capable of C3 (during ACPI cstate init), we
disable local APIC timer and switch to using a broadcast from external timer
interrupt (IRQ 0). This is needed because Intel CPUs stop the local
APIC timer in C3.  This is currently only enabled for Intel CPUs.

Patch below adds the code for i386 and also the ACPI hunk.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
index 41c5b2dc6200..a14d594bfbeb 100644
--- a/arch/i386/kernel/time.c
+++ b/arch/i386/kernel/time.c
@@ -302,6 +302,12 @@ irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
         do_timer_interrupt(irq, regs);
 
         write_sequnlock(&xtime_lock);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+        if (using_apic_timer)
+                smp_send_timer_broadcast_ipi(regs);
+#endif
+
         return IRQ_HANDLED;
 }