[PATCH] PM / runtime: Document new pm_runtime_set_suspended constraint

[Johan Hovold <johan@kernel.org>]

Since commit a8636c89648a ("PM / Runtime: Don't allow to suspend a
device with an active child") it is no longer permitted to set
RPM_SUSPENDED state for a device with active children unless
power.ignore_children is set.

Update the documentation to reflect this.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 Documentation/power/runtime_pm.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 0fde3dcf077a..625549d4c74a 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -435,7 +435,8 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
       PM status to 'suspended' and update its parent's counter of 'active'
       children as appropriate (it is only valid to use this function if
       'power.runtime_error' is set or 'power.disable_depth' is greater than
-      zero)
+      zero); it will fail and return an error code if the device has a child
+      which is active and the 'power.ignore_children' flag is unset
 
   bool pm_runtime_active(struct device *dev);
     - return true if the device's runtime PM status is 'active' or its
-- 
2.13.3