ACPI: EC: PM: Avoid premature returns from acpi_s2idle_wake()

If the EC GPE status is not set after checking all of the other GPEs,
acpi_s2idle_wake() returns 'false', to indicate that the SCI event
that has just triggered is not a system wakeup one, but it does that
without canceling the pending wakeup and re-arming the SCI for system
wakeup which is a mistake, because it may cause s2idle_loop() to busy
spin until the next valid wakeup event.  [If that happens, the first
spurious wakeup is still pending after acpi_s2idle_wake() has
returned, so s2idle_enter() does nothing, acpi_s2idle_wake()
is called again and it sees that the SCI has triggered, but no GPEs
are active, so 'false' is returned again, and so on.]

Fix that by moving all of the GPE checking logic from
acpi_s2idle_wake() to acpi_ec_dispatch_gpe() and making the
latter return 'true' only if a non-EC GPE has triggered and
'false' otherwise, which will cause acpi_s2idle_wake() to
cancel the pending SCI wakeup and re-arm the SCI for system
wakeup regardless of the EC GPE status.

This also addresses a lockup observed on an Elitegroup EF20EA laptop
after attempting to wake it up from suspend-to-idle by a key press.

Fixes: d5406284ff80 ("ACPI: PM: s2idle: Refine active GPEs check")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=207603
Reported-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Fixes: fdde0ff8590b ("ACPI: PM: s2idle: Prevent spurious SCIs from waking up the system")
Link: https://lore.kernel.org/linux-acpi/CAB4CAwdqo7=MvyG_PE+PGVfeA17AHF5i5JucgaKqqMX6mjArbQ@mail.gmail.com/
Reported-by: Chris Chiu <chiu@endlessm.com>
Tested-by: Chris Chiu <chiu@endlessm.com>
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 4edc8a3ce40f..3850704570c0 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -1013,21 +1013,11 @@ static bool acpi_s2idle_wake(void)
 		if (acpi_check_wakeup_handlers())
 			return true;
 
-		/*
-		 * If the status bit is set for any enabled GPE other than the
-		 * EC one, the wakeup is regarded as a genuine one.
-		 */
-		if (acpi_ec_other_gpes_active())
+		/* Check non-EC GPE wakeups and dispatch the EC GPE. */
+		if (acpi_ec_dispatch_gpe())
 			return true;
 
 		/*
-		 * If the EC GPE status bit has not been set, the wakeup is
-		 * regarded as a spurious one.
-		 */
-		if (!acpi_ec_dispatch_gpe())
-			return false;
-
-		/*
 		 * Cancel the wakeup and process all pending events in case
 		 * there are any wakeup ones in there.
 		 *