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

Pavel Machek
2015-02-22T12:27:57Z

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@gmail.com>

Acked-by: Pavel Machek <pavel@ucw.cz>

(Does this need documentation in kernel-parameters.txt or in place
where pm_test is documented?)

Thanks,
Pavel

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