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PM / sleep: add configurable delay for pm_test

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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 <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Reviewed-by: Kevin Cernekee <[email protected]>
Acked-by: Florian Fainelli <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
This commit is contained in:
Brian Norris 2015-02-22 21:16:49 -08:00 • committed by Rafael J. Wysocki
commit 1d4a9c17d4
3 changed files with 24 additions and 6 deletions
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13
kernel/power/suspend.c
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@ -28,6 +28,7 @@
#include <linux/ftrace.h>
#include <trace/events/power.h>
#include <linux/compiler.h>
#include <linux/moduleparam.h>
#include "power.h"
@ -233,12 +234,20 @@ static bool platform_suspend_again(suspend_state_t state)
suspend_ops->suspend_again() : false;
}
#ifdef CONFIG_PM_DEBUG
static unsigned int pm_test_delay = 5;
module_param(pm_test_delay, uint, 0644);
MODULE_PARM_DESC(pm_test_delay,
"Number of seconds to wait before resuming from suspend test");
#endif
static int suspend_test(int level)
{
#ifdef CONFIG_PM_DEBUG
if (pm_test_level == level) {
printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n");
mdelay(5000);
printk(KERN_INFO "suspend debug: Waiting for %d second(s).\n",
pm_test_delay);
mdelay(pm_test_delay * 1000);
return 1;
}
#endif /* !CONFIG_PM_DEBUG */