ACPI: processor: idle: Only flush cache on entering C3

According to ACPI 6.4, Section 8.2, CPU cache flushing required on
entering the C3 power state.

Avoid flushing the cache on entering other C-states.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 4b906bb527e8ccc99f6c827d6d04ce303c8dd6e3..d94794bc269e554b10e57343491434017cbe1174 100644 (file)
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -565,7 +565,8 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
 {
        struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
 
-       ACPI_FLUSH_CPU_CACHE();
+       if (cx->type == ACPI_STATE_C3)
+               ACPI_FLUSH_CPU_CACHE();
 
        while (1) {