power: catch wake-up requests in suspend_again

It is possible during the processing of suspend_again() that a
wake-up request (i.e. pm_stay_awake()) be made by a driver in response
to an outside event (i.e. hw interrupt, etc.). Currently, when
suspend_again() requests to re-enter suspend, suspend_enter() runs
to re-enter suspend. The pm_wakeup_pending() function is called to check
for any wake-up requests. However, this function is essentially disabled
because the events_check_enabled flag is set to false by the previous
run through suspend_enter(). This causes any wake-up request made
during the processing of suspend_again() to be delayed until the next
time the kernel resumes sometime in the future.

To resolve this issue, if suspend_again() votes to re-enter
suspend_enter() the count of wake-up requests is re-evaluated
and the events_check_enabled flag set correctly based on the
presence of wake-up requests that occurred during suspend_again().

Signed-off-by: Joe Swantek <jswantek@motorola.com>
Reviewed-by: Patrick Auchter <auchter@motorola.com>
Reviewed-by: Christopher Fries <cfries@motorola.com>
SLTApproved: Christopher Fries <cfries@motorola.com>
Reviewed-by: Ravi Chebolu <arc095@motorola.com>
Reviewed-by: Fred Fettinger <fettinge@motorola.com>
Reviewed-by: Jeffrey Carlyle <jeff.carlyle@motorola.com>
Reviewed-by: Russell Knize <rknize@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>

kernel/power/suspend.c

@@ -116,6 +116,28 @@ int suspend_valid_only_mem(suspend_state_t state)
 }
 EXPORT_SYMBOL_GPL(suspend_valid_only_mem);
 
+static bool platform_suspend_again(void)
+{
+	int count;
+	bool suspend = suspend_ops->suspend_again ?
+		suspend_ops->suspend_again() : false;
+
+	if (suspend) {
+		/*
+		 * pm_get_wakeup_count() gets an updated count of wakeup events
+		 * that have occured and will return false (i.e. abort suspend)
+		 * if a wakeup event has been started during suspend_again() and
+		 * is still active. pm_save_wakeup_count() stores the count
+		 * and enables pm_wakeup_pending() to properly analyze wakeup
+		 * events before entering suspend in suspend_enter().
+		 */
+		suspend = pm_get_wakeup_count(&count, false) &&
+			  pm_save_wakeup_count(count);
+	}
+
+	return suspend;
+}
+
 static int suspend_test(int level)
 {
 #ifdef CONFIG_PM_DEBUG
@@ -300,7 +322,7 @@ int suspend_devices_and_enter(suspend_state_t state)
 	do {
 		error = suspend_enter(state, &wakeup);
 	} while (!error && !wakeup && need_suspend_ops(state)
-		&& suspend_ops->suspend_again && suspend_ops->suspend_again());
+		&& platform_suspend_again());
 
  Resume_devices:
 	suspend_test_start();