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

Revert commit 87ebbb8c612b ("ACPI: processor: idle: Only flush cache
on entering C3") that broke the assumptions of the acpi_idle_play_dead()
callers.

Namely, the CPU cache must always be flushed in acpi_idle_play_dead(),
regardless of the target C-state that is going to be requested, because
this is likely to be part of a CPU offline procedure or preparation for
entering a system-wide sleep state and the lack of synchronization
between the CPU cache and RAM may lead to problems going forward, for
example when the CPU is brought back online.

In particular, it breaks resume from suspend-to-RAM on Lenovo ThinkPad
C13 which fails occasionally until the problematic commit is reverted.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
[ rjw: Changelog ]
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 32b20efff5f83c9fab837057872002a20bed841a..4556c86c34659e55a6ca82c8a769c37f78ec79c1 100644 (file)
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -570,8 +570,7 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
 {
        struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
 
-       if (cx->type == ACPI_STATE_C3)
-               ACPI_FLUSH_CPU_CACHE();
+       ACPI_FLUSH_CPU_CACHE();
 
        while (1) {