[PATCH 6/6] ACPI / idle: Implement ->enter_freeze callback routine

Rafael J. Wysocki
2015-02-11T03:42:59Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Add an ->enter_freeze callback routine, acpi_idle_enter_freeze(), to
the ACPI cpuidle driver and point ->enter_freeze to it for all the
C2-type and C3-type states that don't need to fall back to C1
(which may be halt-induced and that will re-enable interrupts on
exit from idle, which ->enter_freeze cannot do).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/processor_idle.c | 48 +++++++++++++++++++++++++++++++++++-------
1 file changed, 40 insertions(+), 8 deletions(-)

Index: linux-pm/drivers/acpi/processor_idle.c
===================================================================
--- linux-pm.orig/drivers/acpi/processor_idle.c
+++ linux-pm/drivers/acpi/processor_idle.c
@@ -732,9 +732,8 @@ static int acpi_idle_play_dead(struct cp

static bool acpi_idle_fallback_to_c1(struct acpi_processor *pr)
{
- return IS_ENABLED(CONFIG_HOTPLUG_CPU) && num_online_cpus() > 1 &&
- !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED) &&
- !pr->flags.has_cst;
+ return IS_ENABLED(CONFIG_HOTPLUG_CPU) && !pr->flags.has_cst &&
+ !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED);
}

static int c3_cpu_count;
@@ -744,9 +743,10 @@ static DEFINE_RAW_SPINLOCK(c3_lock);
* acpi_idle_enter_bm - enters C3 with proper BM handling
* @pr: Target processor
* @cx: Target state context
+ * @timer_bc: Whether or not to change timer mode to broadcast
*/
static void acpi_idle_enter_bm(struct acpi_processor *pr,
- struct acpi_processor_cx *cx)
+ struct acpi_processor_cx *cx, bool timer_bc)
{
acpi_unlazy_tlb(smp_processor_id());

@@ -754,7 +754,8 @@ static void acpi_idle_enter_bm(struct ac
* Must be done before busmaster disable as we might need to
* access HPET !
*/
- lapic_timer_state_broadcast(pr, cx, 1);
+ if (timer_bc)
+ lapic_timer_state_broadcast(pr, cx, 1);

/*
* disable bus master
@@ -784,7 +785,8 @@ static void acpi_idle_enter_bm(struct ac
raw_spin_unlock(&c3_lock);
}

- lapic_timer_state_broadcast(pr, cx, 0);
+ if (timer_bc)
+ lapic_timer_state_broadcast(pr, cx, 0);
}

static int acpi_idle_enter(struct cpuidle_device *dev,
@@ -798,12 +800,12 @@ static int acpi_idle_enter(struct cpuidl
return -EINVAL;

if (cx->type != ACPI_STATE_C1) {
- if (acpi_idle_fallback_to_c1(pr)) {
+ if (acpi_idle_fallback_to_c1(pr) && num_online_cpus() > 1) {
index = CPUIDLE_DRIVER_STATE_START;
cx = per_cpu(acpi_cstate[index], dev->cpu);
} else if (cx->type == ACPI_STATE_C3 && pr->flags.bm_check) {
if (cx->bm_sts_skip || !acpi_idle_bm_check()) {
- acpi_idle_enter_bm(pr, cx);
+ acpi_idle_enter_bm(pr, cx, true);
return index;
} else if (drv->safe_state_index >= 0) {
index = drv->safe_state_index;
@@ -827,6 +829,27 @@ static int acpi_idle_enter(struct cpuidl
return index;
}

+static void acpi_idle_enter_freeze(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
+
+ if (cx->type == ACPI_STATE_C3) {
+ struct acpi_processor *pr = __this_cpu_read(processors);
+
+ if (unlikely(!pr))
+ return;
+
+ if (pr->flags.bm_check) {
+ acpi_idle_enter_bm(pr, cx, false);
+ return;
+ } else {
+ ACPI_FLUSH_CPU_CACHE();
+ }
+ }
+ acpi_idle_do_entry(cx);
+}
+
struct cpuidle_driver acpi_idle_driver = {
.name = "acpi_idle",
.owner = THIS_MODULE,
@@ -925,6 +948,15 @@ static int acpi_processor_setup_cpuidle_
state->enter_dead = acpi_idle_play_dead;
drv->safe_state_index = count;
}
+ /*
+ * Halt-induced C1 is not good for ->enter_freeze, because it
+ * re-enables interrupts on exit. Moreover, C1 is generally not
+ * particularly interesting from the suspend-to-idle angle, so
+ * avoid C1 and the situations in which we may need to fall back
+ * to it altogether.
+ */
+ if (cx->type != ACPI_STATE_C1 && !acpi_idle_fallback_to_c1(pr))
+ state->enter_freeze = acpi_idle_enter_freeze;

count++;
if (count == CPUIDLE_STATE_MAX)