linux/kernel/power/main.c, branch v3.16

PM / hibernate: introduce "nohibernate" boot parameter

2014-06-16T21:29:39Z

To support using kernel features that are not compatible with hibernation, this creates the "nohibernate" kernel boot parameter to disable both hibernation and resume. This allows hibernation support to be a boot-time choice instead of only a compile-time choice. Signed-off-by: Kees Cook Acked-by: Pavel Machek Signed-off-by: Rafael J. Wysocki

PM / sleep: Introduce command line argument for sleep state enumeration

2014-05-26T11:40:59Z

On some systems the platform doesn't support neither PM_SUSPEND_MEM nor PM_SUSPEND_STANDBY, so PM_SUSPEND_FREEZE is the only available system sleep state. However, some user space frameworks only use the "mem" and (sometimes) "standby" sleep state labels, so the users of those systems need to modify user space in order to be able to use system suspend at all and that is not always possible. For this reason, add a new kernel command line argument, relative_sleep_states, allowing the users of those systems to change the way in which the kernel assigns labels to system sleep states. Namely, for relative_sleep_states=1, the "mem", "standby" and "freeze" labels will enumerate the available system sleem states from the deepest to the shallowest, respectively, so that "mem" is always present in /sys/power/state and the other state strings may or may not be presend depending on what is supported by the platform. Update system sleep states documentation to reflect this change. Signed-off-by: Rafael J. Wysocki

PM / sleep: Use valid_state() for platform-dependent sleep states only

2014-05-26T11:40:53Z

Use the observation that, for platform-dependent sleep states (PM_SUSPEND_STANDBY, PM_SUSPEND_MEM), a given state is either always supported or always unsupported and store that information in pm_states[] instead of calling valid_state() every time we need to check it. Also do not use valid_state() for PM_SUSPEND_FREEZE, which is always valid, and move the pm_test_level validity check for PM_SUSPEND_FREEZE directly into enter_state(). Signed-off-by: Rafael J. Wysocki

PM / sleep: Add state field to pm_states[] entries

2014-05-26T11:40:47Z

To allow sleep states corresponding to the "mem", "standby" and "freeze" lables to be different from the pm_states[] indexes of those strings, introduce struct pm_sleep_state, consisting of a string label and a state number, and turn pm_states[] into an array of objects of that type. This modification should not lead to any functional changes. Signed-off-by: Rafael J. Wysocki

PM: Add missing "freeze" state

2014-03-11T23:54:53Z

Fix descriptions of /sys/power/state in the documentation and in a code comment. Signed-off-by: Geert Uytterhoeven Reviewed-by: Srivatsa S. Bhat Acked-by: Pavel Machek [rjw: Changelog] Signed-off-by: Rafael J. Wysocki

PM / Sleep: Warn about system time after resume with pm_trace

2013-06-27T20:14:46Z

pm_trace uses the system's Real Time Clock (RTC) to save the magic number. The reason for this is that the RTC is the only reliably available piece of hardware during resume operations where a value can be set that will survive a reboot. Consequence is that after a resume (even if it is successful) your system clock will have a value corresponding to the magic number instead of the correct date/time! It is therefore advisable to use a program like ntp-date or rdate to reset the correct date/time from an external time source when using this trace option. There is no run-time message to warn users of the consequences of enabling pm_trace. Adding a warning message to pm_trace_store() will serve as a reminder to users to set the system date and time after resume. Signed-off-by: Shuah Khan Acked-by: Pavel Machek Signed-off-by: Rafael J. Wysocki

PM / Sleep: Print last wakeup source on failed wakeup_count write

2013-06-20T22:35:12Z

Commit a938da06 introduced a useful little log message to tell users/debuggers which wakeup source aborted a suspend. However, this message is only printed if the abort happens during the in-kernel suspend path (after writing /sys/power/state). The full specification of the /sys/power/wakeup_count facility allows user-space power managers to double-check if wakeups have already happened before it actually tries to suspend (e.g. while it was running user-space pre-suspend hooks), by writing the last known wakeup_count value to /sys/power/wakeup_count. This patch changes the sysfs handler for that node to also print said log message if that write fails, so that we can figure out the offending wakeup source for both kinds of suspend aborts. Signed-off-by: Julius Werner Signed-off-by: Rafael J. Wysocki

suspend: enable freeze timeout configuration through sys

2013-02-09T21:32:48Z

At present, the value of timeout for freezing is 20s, which is meaningless in case that one thread is frozen with mutex locked and another thread is trying to lock the mutex, as this time of freezing will fail unavoidably. And if there is no new wakeup event registered, the system will waste at most 20s for such meaningless trying of freezing. With this patch, the value of timeout can be configured to smaller value, so such meaningless trying of freezing will be aborted in earlier time, and later freezing can be also triggered in earlier time. And more power will be saved. In normal case on mobile phone, it costs real little time to freeze processes. On some platform, it only costs about 20ms to freeze user space processes and 10ms to freeze kernel freezable threads. Signed-off-by: Liu Chuansheng Signed-off-by: Li Fei Signed-off-by: Rafael J. Wysocki

PM: Introduce suspend state PM_SUSPEND_FREEZE

2013-02-09T21:30:44Z

PM_SUSPEND_FREEZE state is a general state that does not need any platform specific support, it equals frozen processes + suspended devices + idle processors. Compared with PM_SUSPEND_MEMORY, PM_SUSPEND_FREEZE saves less power because the system is still in a running state. PM_SUSPEND_FREEZE has less resume latency because it does not touch BIOS, and the processors are in idle state. Compared with RTPM/idle, PM_SUSPEND_FREEZE saves more power as 1. the processor has longer sleep time because processes are frozen. The deeper c-state the processor supports, more power saving we can get. 2. PM_SUSPEND_FREEZE uses system suspend code path, thus we can get more power saving from the devices that does not have good RTPM support. This state is useful for 1) platforms that do not have STR, or have a broken STR. 2) platforms that have an extremely low power idle state, which can be used to replace STR. The following describes how PM_SUSPEND_FREEZE state works. 1. echo freeze > /sys/power/state 2. the processes are frozen. 3. all the devices are suspended. 4. all the processors are blocked by a wait queue 5. all the processors idles and enters (Deep) c-state. 6. an interrupt fires. 7. a processor is woken up and handles the irq. 8. if it is a general event, a) the irq handler runs and quites. b) goto step 4. 9. if it is a real wake event, say, power button pressing, keyboard touch, mouse moving, a) the irq handler runs and activate the wakeup source b) wakeup_source_activate() notifies the wait queue. c) system starts resuming from PM_SUSPEND_FREEZE 10. all the devices are resumed. 11. all the processes are unfrozen. 12. system is back to working. Known Issue: The wakeup of this new PM_SUSPEND_FREEZE state may behave differently from the previous suspend state. Take ACPI platform for example, there are some GPEs that only enabled when the system is in sleep state, to wake the system backk from S3/S4. But we are not touching these GPEs during transition to PM_SUSPEND_FREEZE. This means we may lose some wake event. But on the other hand, as we do not disable all the Interrupts during PM_SUSPEND_FREEZE, we may get some extra "wakeup" Interrupts, that are not available for S3/S4. The patches has been tested on an old Sony laptop, and here are the results: Average Power: 1. RPTM/idle for half an hour: 14.8W, 12.6W, 14.1W, 12.5W, 14.4W, 13.2W, 12.9W 2. Freeze for half an hour: 11W, 10.4W, 9.4W, 11.3W 10.5W 3. RTPM/idle for three hours: 11.6W 4. Freeze for three hours: 10W 5. Suspend to Memory: 0.5~0.9W Average Resume Latency: 1. RTPM/idle with a black screen: (From pressing keyboard to screen back) Less than 0.2s 2. Freeze: (From pressing power button to screen back) 2.50s 3. Suspend to Memory: (From pressing power button to screen back) 4.33s >From the results, we can see that all the platforms should benefit from this patch, even if it does not have Low Power S0. Signed-off-by: Zhang Rui Signed-off-by: Rafael J. Wysocki

PM / sysfs: replace strict_str* with kstrto*

2012-11-14T23:37:08Z

Replace strict_strtoul() with kstrtoul() in pm_async_store() and pm_qos_power_write(). [rjw: Modified subject and changelog.] Signed-off-by: Daniel Walter Acked-by: Pavel Machek Signed-off-by: Rafael J. Wysocki