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 adds a companion sysfs file (/sys/power/pm_test_delay) that allows user-space to configure how long the system waits in this test state before resuming. It also updates the PM debugging documentation to mention the new file. Signed-off-by: Brian Norris <[email protected]> --- Documentation/power/basic-pm-debugging.txt | 14 ++++++++------ kernel/power/main.c | 27 +++++++++++++++++++++++++++ kernel/power/power.h | 5 +++++ kernel/power/suspend.c | 8 ++++++-- 4 files changed, 46 insertions(+), 8 deletions(-) diff --git a/Documentation/power/basic-pm-debugging.txt b/Documentation/power/basic-pm-debugging.txt index edeecd447d23..bd9f27ae99fe 100644 --- a/Documentation/power/basic-pm-debugging.txt +++ b/Documentation/power/basic-pm-debugging.txt @@ -75,12 +75,14 @@ you should do the following: # echo platform > /sys/power/disk # echo disk > /sys/power/state -Then, the kernel will try to freeze processes, suspend devices, wait 5 seconds, -resume devices and thaw processes. If "platform" is written to -/sys/power/pm_test , then after suspending devices the kernel will additionally -invoke the global control methods (eg. ACPI global control methods) used to -prepare the platform firmware for hibernation. Next, it will wait 5 seconds and -invoke the platform (eg. ACPI) global methods used to cancel hibernation etc. +Then, the kernel will try to freeze processes, suspend devices, wait a few +seconds (5 by default, but configurable via /sys/power/pm_test_delay), resume +devices and thaw processes. If "platform" is written to /sys/power/pm_test, +then after suspending devices the kernel will additionally invoke the global +control methods (eg. ACPI global control methods) used to prepare the platform +firmware for hibernation. Next, it will wait a configurable number of seconds +and invoke the platform (eg. ACPI) global methods used to cancel hibernation +etc. Writing "none" to /sys/power/pm_test causes the kernel to switch to the normal hibernation/suspend operations. Also, when open for reading, /sys/power/pm_test diff --git a/kernel/power/main.c b/kernel/power/main.c index 9a59d042ea84..4d242c8b43a0 100644 --- a/kernel/power/main.c +++ b/kernel/power/main.c @@ -73,6 +73,7 @@ power_attr(pm_async); #ifdef CONFIG_PM_DEBUG int pm_test_level = TEST_NONE; +int pm_test_seconds = PM_TEST_DELAY_DEFAULT; static const char * const pm_tests[__TEST_AFTER_LAST] = { [TEST_NONE] = "none", @@ -132,6 +133,31 @@ static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr, } power_attr(pm_test); + +static ssize_t pm_test_delay_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%d\n", pm_test_seconds); +} + +static ssize_t pm_test_delay_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t n) +{ + int val; + + if (kstrtoint(buf, 10, &val)) + return -EINVAL; + + if (val < 0) + return -EINVAL; + + pm_test_seconds = val; + + return n; +} + +power_attr(pm_test_delay); #endif /* CONFIG_PM_DEBUG */ #ifdef CONFIG_DEBUG_FS @@ -601,6 +627,7 @@ static struct attribute * g[] = { #endif #ifdef CONFIG_PM_DEBUG &pm_test_attr.attr, + &pm_test_delay_attr.attr, #endif #ifdef CONFIG_PM_SLEEP_DEBUG &pm_print_times_attr.attr, diff --git a/kernel/power/power.h b/kernel/power/power.h index 5d49dcac2537..28111795da71 100644 --- a/kernel/power/power.h +++ b/kernel/power/power.h @@ -230,6 +230,11 @@ enum { extern int pm_test_level; +/* Default to 5 second delay */ +#define PM_TEST_DELAY_DEFAULT 5 + +extern int pm_test_seconds; + #ifdef CONFIG_SUSPEND_FREEZER static inline int suspend_freeze_processes(void) { diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 6dadb25cb0d8..2372a99d4356 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -196,8 +196,12 @@ 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); + int i; + + pr_info("suspend debug: waiting for %d second(s)\n", + pm_test_seconds); + for (i = 0; i < pm_test_seconds; i++) + mdelay(1000); return 1; } #endif /* !CONFIG_PM_DEBUG */ -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
