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Subject[patch 30/46] ACPI keep track of timer broadcasting
From: Thomas Gleixner <tglx@linutronix.de>

This is a preperatory patch for highres/dyntick:

- replace the big #ifdef ARCH_APICTIMER_STOPS_ON_C3 hackery by functions

- remove the double switch in the power verify function (in the worst case
we switched ipi to apic and 20usec later apic to ipi)

- keep track of the the state which stops local APIC timer

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Len Brown <len.brown@intel.com>
Cc: <linux-acpi@vger.kernel.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

drivers/acpi/processor_idle.c | 67 ++++++++++++++++++++++++++++++------------
include/acpi/processor.h | 1
2 files changed, 49 insertions(+), 19 deletions(-)

Index: linux-2.6.20-rc4-mm1-bo/drivers/acpi/processor_idle.c
===================================================================
--- linux-2.6.20-rc4-mm1-bo.orig/drivers/acpi/processor_idle.c
+++ linux-2.6.20-rc4-mm1-bo/drivers/acpi/processor_idle.c
@@ -250,6 +250,49 @@ static void acpi_cstate_enter(struct acp
}
}

+#ifdef ARCH_APICTIMER_STOPS_ON_C3
+
+/*
+ * Some BIOS implementations switch to C3 in the published C2 state. This seems
+ * to be a common problem on AMD boxen.
+ */
+static void acpi_timer_check_state(int state, struct acpi_processor *pr,
+ struct acpi_processor_cx *cx)
+{
+ struct acpi_processor_power *pwr = &pr->power;
+
+ /*
+ * Check, if one of the previous states already marked the lapic
+ * unstable
+ */
+ if (pwr->timer_broadcast_on_state < state)
+ return;
+
+ if(cx->type == ACPI_STATE_C3 ||
+ boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ pr->power.timer_broadcast_on_state = state;
+ return;
+ }
+}
+
+static void acpi_propagate_timer_broadcast(struct acpi_processor *pr)
+{
+ cpumask_t mask = cpumask_of_cpu(pr->id);
+
+ if (pr->power.timer_broadcast_on_state < INT_MAX)
+ on_each_cpu(switch_APIC_timer_to_ipi, &mask, 1, 1);
+ else
+ on_each_cpu(switch_ipi_to_APIC_timer, &mask, 1, 1);
+}
+
+#else
+
+static void acpi_timer_check_state(int state, struct acpi_processor *pr,
+ struct acpi_processor_cx *cstate) { }
+static void acpi_propagate_timer_broadcast(struct acpi_processor *pr) { }
+
+#endif
+
static void acpi_processor_idle(void)
{
struct acpi_processor *pr = NULL;
@@ -920,11 +963,7 @@ static int acpi_processor_power_verify(s
unsigned int i;
unsigned int working = 0;

-#ifdef ARCH_APICTIMER_STOPS_ON_C3
- int timer_broadcast = 0;
- cpumask_t mask = cpumask_of_cpu(pr->id);
- on_each_cpu(switch_ipi_to_APIC_timer, &mask, 1, 1);
-#endif
+ pr->power.timer_broadcast_on_state = INT_MAX;

for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
struct acpi_processor_cx *cx = &pr->power.states[i];
@@ -936,21 +975,14 @@ static int acpi_processor_power_verify(s

case ACPI_STATE_C2:
acpi_processor_power_verify_c2(cx);
-#ifdef ARCH_APICTIMER_STOPS_ON_C3
- /* Some AMD systems fake C3 as C2, but still
- have timer troubles */
- if (cx->valid &&
- boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
- timer_broadcast++;
-#endif
+ if (cx->valid)
+ acpi_timer_check_state(i, pr, cx);
break;

case ACPI_STATE_C3:
acpi_processor_power_verify_c3(pr, cx);
-#ifdef ARCH_APICTIMER_STOPS_ON_C3
if (cx->valid)
- timer_broadcast++;
-#endif
+ acpi_timer_check_state(i, pr, cx);
break;
}

@@ -958,10 +990,7 @@ static int acpi_processor_power_verify(s
working++;
}

-#ifdef ARCH_APICTIMER_STOPS_ON_C3
- if (timer_broadcast)
- on_each_cpu(switch_APIC_timer_to_ipi, &mask, 1, 1);
-#endif
+ acpi_propagate_timer_broadcast(pr);

return (working);
}
Index: linux-2.6.20-rc4-mm1-bo/include/acpi/processor.h
===================================================================
--- linux-2.6.20-rc4-mm1-bo.orig/include/acpi/processor.h
+++ linux-2.6.20-rc4-mm1-bo/include/acpi/processor.h
@@ -79,6 +79,7 @@ struct acpi_processor_power {
u32 bm_activity;
int count;
struct acpi_processor_cx states[ACPI_PROCESSOR_MAX_POWER];
+ int timer_broadcast_on_state;
};

/* Performance Management */
--

-
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