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-rw-r--r--Documentation/power/basic-pm-debugging.txt26
1 files changed, 25 insertions, 1 deletions
diff --git a/Documentation/power/basic-pm-debugging.txt b/Documentation/power/basic-pm-debugging.txt
index ddd78172ef73..40a4c65f380a 100644
--- a/Documentation/power/basic-pm-debugging.txt
+++ b/Documentation/power/basic-pm-debugging.txt
@@ -173,7 +173,7 @@ kernel messages using the serial console. This may provide you with some
information about the reasons of the suspend (resume) failure. Alternatively,
it may be possible to use a FireWire port for debugging with firescope
(ftp://ftp.firstfloor.org/pub/ak/firescope/). On x86 it is also possible to
-use the PM_TRACE mechanism documented in Documentation/s2ram.txt .
+use the PM_TRACE mechanism documented in Documentation/power/s2ram.txt .
2. Testing suspend to RAM (STR)
@@ -201,3 +201,27 @@ case, you may be able to search for failing drivers by following the procedure
analogous to the one described in section 1. If you find some failing drivers,
you will have to unload them every time before an STR transition (ie. before
you run s2ram), and please report the problems with them.
+
+There is a debugfs entry which shows the suspend to RAM statistics. Here is an
+example of its output.
+ # mount -t debugfs none /sys/kernel/debug
+ # cat /sys/kernel/debug/suspend_stats
+ success: 20
+ fail: 5
+ failed_freeze: 0
+ failed_prepare: 0
+ failed_suspend: 5
+ failed_suspend_noirq: 0
+ failed_resume: 0
+ failed_resume_noirq: 0
+ failures:
+ last_failed_dev: alarm
+ adc
+ last_failed_errno: -16
+ -16
+ last_failed_step: suspend
+ suspend
+Field success means the success number of suspend to RAM, and field fail means
+the failure number. Others are the failure number of different steps of suspend
+to RAM. suspend_stats just lists the last 2 failed devices, error number and
+failed step of suspend.