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authorBoris Ostrovsky <boris.ostrovsky@amd.com>2012-03-13 19:55:09 +0100
committerLen Brown <len.brown@intel.com>2012-03-30 03:23:01 -0400
commit1a022e3f1be11730bd8747b1af96a0274bf6356e (patch)
treed3c95b68626ac7d963ac3a85a07dae1cfc011906 /drivers/acpi
parente07510585a88c0f6c6c728e2e006aa913496d4ae (diff)
downloadlinux-1a022e3f1be11730bd8747b1af96a0274bf6356e.tar.bz2
idle, x86: Allow off-lined CPU to enter deeper C states
Currently when a CPU is off-lined it enters either MWAIT-based idle or, if MWAIT is not desired or supported, HLT-based idle (which places the processor in C1 state). This patch allows processors without MWAIT support to stay in states deeper than C1. Signed-off-by: Boris Ostrovsky <boris.ostrovsky@amd.com> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/processor_idle.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 0e8e2de2ed3e..6b1d32a161ae 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -770,6 +770,35 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev,
return index;
}
+
+/**
+ * acpi_idle_play_dead - enters an ACPI state for long-term idle (i.e. off-lining)
+ * @dev: the target CPU
+ * @index: the index of suggested state
+ */
+static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
+{
+ struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
+ struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
+
+ ACPI_FLUSH_CPU_CACHE();
+
+ while (1) {
+
+ if (cx->entry_method == ACPI_CSTATE_HALT)
+ halt();
+ else if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
+ inb(cx->address);
+ /* See comment in acpi_idle_do_entry() */
+ inl(acpi_gbl_FADT.xpm_timer_block.address);
+ } else
+ return -ENODEV;
+ }
+
+ /* Never reached */
+ return 0;
+}
+
/**
* acpi_idle_enter_simple - enters an ACPI state without BM handling
* @dev: the target CPU
@@ -1077,12 +1106,14 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
state->flags |= CPUIDLE_FLAG_TIME_VALID;
state->enter = acpi_idle_enter_c1;
+ state->enter_dead = acpi_idle_play_dead;
drv->safe_state_index = count;
break;
case ACPI_STATE_C2:
state->flags |= CPUIDLE_FLAG_TIME_VALID;
state->enter = acpi_idle_enter_simple;
+ state->enter_dead = acpi_idle_play_dead;
drv->safe_state_index = count;
break;