Le 22/02/2015 00:26, Brian Norris a écrit :
> 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 <computersforpe...@gmail.com>
Acked-by: Florian Fainelli <f.faine...@gmail.com>
> ---
> v2: - make this a module param instead of an explicit sysfs file
> - drop the for loop; mdelay() does the same loop internally
> - decrease +36 lines of code and +2 lines of doc, to +6 lines of code and
> +2 lines of doc
>
> kernel/power/suspend.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index c347e3ce3a55..aee23dab0a55 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -28,6 +28,7 @@
> #include <linux/ftrace.h>
> #include <trace/events/power.h>
> #include <linux/compiler.h>
> +#include <linux/moduleparam.h>
>
> #include "power.h"
>
> @@ -204,12 +205,20 @@ 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 */
>
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