PM / Sleep: add knob for printing device resume times

Added a new knob called /sys/power/pm_print_times. Setting it to 1
enables printing of time taken by devices to suspend and resume.
Setting it to 0 disables this printing (unless overridden by
initcall_debug kernel command line option).

Signed-off-by: Sameer Nanda <snanda@chromium.org>
Acked-by: Greg KH <gregkh@linuxfoundation.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 13 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index 31725ffeeb3a..217772615d02 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -231,3 +231,16 @@ Description:
                 Reads from this file return a string consisting of the names of
                 wakeup sources created with the help of /sys/power/wake_lock
                 that are inactive at the moment, separated with spaces.
+
+What:           /sys/power/pm_print_times
+Date:           May 2012
+Contact:        Sameer Nanda <snanda@chromium.org>
+Description:
+                The /sys/power/pm_print_times file allows user space to
+                control whether the time taken by devices to suspend and
+                resume is printed.  These prints are useful for hunting down
+                devices that take too long to suspend or resume.
+
+                Writing a "1" enables this printing while writing a "0"
+                disables it.  The default value is "0".  Reading from this file
+                will display the current value.