x86-32: AMD c1e force timer broadcast late

This patch is not needed in 2.6.27 because it has new c1e-aware idle code.

In kernel 2.6.26 the 32-bit x86 timers are started earlier than before.
This breaks AMD c1e detection trying to force timer broadcast for the
local apic timer. Copy the code from the 64-bit kernel to force timer
broadcast late.

Reference:
http://bugzilla.kernel.org/show_bug.cgi?id=11427

Signed-off-by: Chuck Ebbert <cebbert@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c
index 4b99b1bdeb6cbb090e5868138922b259da7d98fe..6815189e8450d6e8ab8cd0bd44a5a803a5e85bba 100644 (file)
--- a/arch/x86/kernel/apic_32.c
+++ b/arch/x86/kernel/apic_32.c
@@ -552,8 +552,31 @@ void __init setup_boot_APIC_clock(void)
        setup_APIC_timer();
 }
 
-void __devinit setup_secondary_APIC_clock(void)
+/*
+ * AMD C1E enabled CPUs have a real nasty problem: Some BIOSes set the
+ * C1E flag only in the secondary CPU, so when we detect the wreckage
+ * we already have enabled the boot CPU local apic timer. Check, if
+ * disable_apic_timer is set and the DUMMY flag is cleared. If yes,
+ * set the DUMMY flag again and force the broadcast mode in the
+ * clockevents layer.
+ */
+static void __cpuinit check_boot_apic_timer_broadcast(void)
+{
+       if (!local_apic_timer_disabled ||
+           (lapic_clockevent.features & CLOCK_EVT_FEAT_DUMMY))
+               return;
+
+       lapic_clockevent.features |= CLOCK_EVT_FEAT_DUMMY;
+
+       local_irq_enable();
+       clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
+                          &boot_cpu_physical_apicid);
+       local_irq_disable();
+}
+
+void __cpuinit setup_secondary_APIC_clock(void)
 {
+       check_boot_apic_timer_broadcast();
        setup_APIC_timer();
 }