Re: [PATCH v2] PM / sleep: add configurable delay for pm_test

From: Kevin Cernekee
Date: Sun Feb 22 2015 - 10:18:35 EST

On Sun, Feb 22, 2015 at 4:27 AM, Pavel Machek <pavel@xxxxxx> wrote:
> On Sun 2015-02-22 00:26:54, Brian Norris wrote:
>> When CONFIG_PM_DEBUG=y, we provide a sysfs file (/sys/power/pm_test) for
>> selecting one of a few suspend test modes, where rather than entering a
>> full suspend state, the kernel will perform some subset of suspend
>> steps, wait 5 seconds, and then resume back to normal operation.
>> This mode is useful for (among other things) observing the state of the
>> system just before entering a sleep mode, for debugging or analysis
>> purposes. However, a constant 5 second wait is not sufficient for some
>> sorts of analysis; for example, on an SoC, one might want to use
>> external tools to probe the power states of various on-chip controllers
>> or clocks.
>> This patch turns this 5 second delay into a configurable module
>> parameter, so users can determine how long to wait in this
>> pseudo-suspend state before resuming the system.
>> Example (wait 30 seconds);
>> # echo 30 > /sys/module/suspend/parameters/pm_test_delay
>> # echo core > /sys/power/pm_test
>> # time echo mem > /sys/power/state
>> ...
>> [ 17.583625] suspend debug: Waiting for 30 second(s).
>> ...
>> real 0m30.381s
>> user 0m0.017s
>> sys 0m0.080s
>> Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
> Acked-by: Pavel Machek <pavel@xxxxxx>
> (Does this need documentation in kernel-parameters.txt or in place
> where pm_test is documented?)

Perhaps both places? Documentation/power/basic-pm-debugging.txt still
has the "wait 5 seconds" verbiage.

Beyond that, it looks good to me:

Reviewed-by: Kevin Cernekee <cernekee@xxxxxxxxxxxx>
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