PM / s2idle: Invoke the ->wake() platform callback earlier

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)
Tested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 3e2b4f5..ccd2d20 100644 (file)
--- a/kernel/power/suspend.c
+++ b/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();