From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
The role of the ->wake() platform callback for suspend-to-idle is to
deal with possible spurious wakeups, among other things. The ACPI
implementation of it, acpi_s2idle_wake(), additionally checks the
conditions for entering the Low Power S0 Idle state by the platform
and reports the ones that have not been met.
However, the ->wake() platform callback is invoked after calling
dpm_noirq_resume_devices(), which means that the power states of some
devices may have changed since s2idle_enter() returned, so some unmet
Low Power S0 Idle conditions may be reported incorrectly as a result
of that.
To avoid these false positives, reorder the invocations of the
dpm_noirq_resume_devices() routine and the ->wake() platform callback
in s2idle_loop().
Fixes: 726fb6b4f2a8 (ACPI / PM: Check low power idle constraints for debug only)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
Tested on Dell XPS13 9360.
---
kernel/power/suspend.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
Index: linux-pm/kernel/power/suspend.c
===================================================================
--- linux-pm.orig/kernel/power/suspend.c
+++ linux-pm/kernel/power/suspend.c
@@ -120,22 +120,26 @@ static void s2idle_loop(void)
* frozen processes + suspended devices + idle processors.
* Thus s2idle_enter() should be called right after
* all devices have been suspended.
+ *
+ * Wakeups during the noirq suspend of devices may be spurious,
+ * so prevent them from terminating the loop right away.
*/
error = dpm_noirq_suspend_devices(PMSG_SUSPEND);
if (!error)
s2idle_enter();
+ else if (error == -EBUSY && pm_wakeup_pending())
+ error = 0;
- dpm_noirq_resume_devices(PMSG_RESUME);
- if (error && (error != -EBUSY || !pm_wakeup_pending())) {
- dpm_noirq_end();
- break;
- }
-
- if (s2idle_ops && s2idle_ops->wake)
+ if (!error && s2idle_ops && s2idle_ops->wake)
s2idle_ops->wake();
+ dpm_noirq_resume_devices(PMSG_RESUME);
+
dpm_noirq_end();
+ if (error)
+ break;
+
if (s2idle_ops && s2idle_ops->sync)
s2idle_ops->sync();
--
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