From: Akihiko Odaki akihiko.odaki@gmail.com
commit dfbba2518aac4204203b0697a894d3b2f80134d3 upstream.
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 Cc: Ketsui esgwpl@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/acpi/processor_idle.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -570,8 +570,7 @@ static int acpi_idle_play_dead(struct cp { 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) {