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idle, x86: Allow off-lined CPU to enter deeper C states

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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>
This commit is contained in:
Boris Ostrovsky
2012-03-13 19:55:09 +01:00
committed by Len Brown
parent e07510585a
commit 1a022e3f1b
4 changed files with 67 additions and 1 deletions
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31
drivers/acpi/processor_idle.c
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@@ -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;