user/sven/linux.git/include/linux/suspend.h, branch v3.3.5

PM / Hibernate: Rewrite unlock_system_sleep() to fix s2disk regression

2012-01-19T22:25:33Z

Commit 33e638b, "PM / Sleep: Use the freezer_count() functions in [un]lock_system_sleep() APIs" introduced an undesirable change in the behaviour of unlock_system_sleep() since freezer_count() internally calls try_to_freeze() - which we don't need in unlock_system_sleep(). And commit bcda53f, "PM / Sleep: Replace mutex_[un]lock(&pm_mutex) with [un]lock_system_sleep()" made these APIs wide-spread. This caused a regression in suspend-to-disk where snapshot_read() and snapshot_write() were getting frozen due to the try_to_freeze embedded in unlock_system_sleep(), since these functions were invoked when the freezing condition was still in effect. Fix this by rewriting unlock_system_sleep() by open-coding freezer_count() and dropping the try_to_freeze() part. Not only will this fix the regression but this will also ensure that the API only does what it is intended to do, and nothing more, under the hood. While at it, make the code more correct and robust by ensuring that the PF_FREEZER_SKIP flag gets cleared with pm_mutex held, to avoid a race with the freezer. Also, to be on the safer side, open-code freezer_do_not_count() as well (inside lock_system_sleep()), to ensure that any unrelated modification to freezer[_do_not]_count() does not break things again! Reported-and-tested-by: Rafael J. Wysocki Signed-off-by: Srivatsa S. Bhat Acked-by: Tejun Heo Signed-off-by: Rafael J. Wysocki

PM / Sleep: Make [un]lock_system_sleep() generic

2011-12-08T22:22:21Z

The [un]lock_system_sleep() APIs were originally introduced to mutually exclude memory hotplug and hibernation. Directly using mutex_lock(&pm_mutex) to achieve mutual exclusion with suspend or hibernation code can lead to freezing failures. However, the APIs [un]lock_system_sleep() can be safely used to achieve the same, without causing freezing failures. So, since it would be beneficial to modify all the existing users of mutex_lock(&pm_mutex) (in all parts of the kernel), so that they use these safe APIs intead, make these APIs generic by removing the restriction that they work only when CONFIG_HIBERNATE_CALLBACKS is set. Moreover, that restriction didn't buy us anything anyway. Suggested-by: Tejun Heo Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki

PM / Sleep: Use the freezer_count() functions in [un]lock_system_sleep() APIs

2011-12-08T22:22:09Z

Now that freezer_count() and freezer_do_not_count() don't have the restriction that they are effective only when called by userspace processes, use them in lock_system_sleep() and unlock_system_sleep() instead of open-coding their parts. Signed-off-by: Srivatsa S. Bhat Acked-by: Tejun Heo Signed-off-by: Rafael J. Wysocki

PM / Memory-hotplug: Avoid task freezing failures

2011-11-23T20:13:16Z

The lock_system_sleep() function is used in the memory hotplug code at several places in order to implement mutual exclusion with hibernation. However, this function tries to acquire the 'pm_mutex' lock using mutex_lock() and hence blocks in TASK_UNINTERRUPTIBLE state if it doesn't get the lock. This would lead to task freezing failures and hence hibernation failure as a consequence, even though the hibernation call path successfully acquired the lock. But it is to be noted that, since this task tries to acquire pm_mutex, if it blocks due to this, we are *100% sure* that this task is not going to run as long as hibernation sequence is in progress, since hibernation releases 'pm_mutex' only at the very end, when everything is done. And this means, this task is going to be anyway blocked for much more longer than what the freezer intends to achieve; which means, freezing and thawing doesn't really make any difference to this task! So, to fix freezing failures, we just ask the freezer to skip freezing this task, since it is already "frozen enough". But instead of calling freezer_do_not_count() and freezer_count() as it is, we use only the relevant parts of those functions, because restrictions such as 'the task should be a userspace one' etc., might not be relevant in this scenario. Signed-off-by: Srivatsa S. Bhat Acked-by: Tejun Heo Signed-off-by: Rafael J. Wysocki

PM / VT: Cleanup #if defined uglyness and fix compile error

2011-10-16T21:28:51Z

Introduce the config option CONFIG_VT_CONSOLE_SLEEP in order to cleanup the #if defined ugliness for the vt suspend support functions. Note that CONFIG_VT_CONSOLE is already dependant on CONFIG_VT. The function pm_set_vt_switch is actually dependant on CONFIG_VT and not CONFIG_PM_SLEEP. This fixes a compile error when CONFIG_PM_SLEEP is not set: drivers/tty/vt/vt_ioctl.c:1794: error: redefinition of 'pm_set_vt_switch' include/linux/suspend.h:17: error: previous definition of 'pm_set_vt_switch' was here Also, remove the incorrect path from the comment in console.c. [rjw: Replaced #if defined() with #ifdef in suspend.h.] Signed-off-by: H Hartley Sweeten Acked-by: Arnd Bergmann Signed-off-by: Rafael J. Wysocki

PM / Hibernate: Include storage keys in hibernation image on s390

2011-10-16T21:27:46Z

For s390 there is one additional byte associated with each page, the storage key. This byte contains the referenced and changed bits and needs to be included into the hibernation image. If the storage keys are not restored to their previous state all original pages would appear to be dirty. This can cause inconsistencies e.g. with read-only filesystems. Signed-off-by: Martin Schwidefsky Signed-off-by: Rafael J. Wysocki

PM / Suspend: Add statistics debugfs file for suspend to RAM

2011-10-16T21:27:45Z

Record S3 failure time about each reason and the latest two failed devices' names in S3 progress. We can check it through 'suspend_stats' entry in debugfs. The motivation of the patch: We are enabling power features on Medfield. Comparing with PC/notebook, a mobile enters/exits suspend-2-ram (we call it s3 on Medfield) far more frequently. If it can't enter suspend-2-ram in time, the power might be used up soon. We often find sometimes, a device suspend fails. Then, system retries s3 over and over again. As display is off, testers and developers don't know what happens. Some testers and developers complain they don't know if system tries suspend-2-ram, and what device fails to suspend. They need such info for a quick check. The patch adds suspend_stats under debugfs for users to check suspend to RAM statistics quickly. If not using this patch, we have other methods to get info about what device fails. One is to turn on CONFIG_PM_DEBUG, but users would get too much info and testers need recompile the system. In addition, dynamic debug is another good tool to dump debug info. But it still doesn't match our utilization scenario closely. 1) user need write a user space parser to process the syslog output; 2) Our testing scenario is we leave the mobile for at least hours. Then, check its status. No serial console available during the testing. One is because console would be suspended, and the other is serial console connecting with spi or HSU devices would consume power. These devices are powered off at suspend-2-ram. Signed-off-by: ShuoX Liu Signed-off-by: Rafael J. Wysocki

notifiers: pm: move pm notifiers into suspend.h

2011-07-26T03:57:15Z

It is not necessary to share the same notifier.h. Signed-off-by: WANG Cong Cc: David Miller Acked-by: "Rafael J. Wysocki" Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

PM / Suspend: Add .suspend_again() callback to suspend_ops

2011-07-15T21:58:19Z

A system or a device may need to control suspend/wakeup events. It may want to wakeup the system after a predefined amount of time or at a predefined event decided while entering suspend for polling or delayed work. Then, it may want to enter suspend again if its predefined wakeup condition is the only wakeup reason and there is no outstanding events; thus, it does not wakeup the userspace unnecessary or unnecessary devices and keeps suspended as long as possible (saving the power). Enabling a system to wakeup after a specified time can be easily achieved by using RTC. However, to enter suspend again immediately without invoking userland and unrelated devices, we need additional features in the suspend framework. Such need comes from: 1. Monitoring a critical device status without interrupts that can wakeup the system. (in-suspend polling) An example is ambient temperature monitoring that needs to shut down the system or a specific device function if it is too hot or cold. The temperature of a specific device may be needed to be monitored as well; e.g., a charger monitors battery temperature in order to stop charging if overheated. 2. Execute critical "delayed work" at suspend. A driver or a system/board may have a delayed work (or any similar things) that it wants to execute at the requested time. For example, some chargers want to check the battery voltage some time (e.g., 30 seconds) after the battery is fully charged and the charger has stopped. Then, the charger restarts charging if the voltage has dropped more than a threshold, which is smaller than "restart-charger" voltage, which is a threshold to restart charging regardless of the time passed. This patch allows to add "suspend_again" callback at struct platform_suspend_ops and let the "suspend_again" callback return true if the system is required to enter suspend again after the current instance of wakeup. Device-wise suspend_again implemented at dev_pm_ops or syscore is not done because: a) suspend_again feature is usually under platform-wise decision and controls the behavior of the whole platform and b) There are very limited devices related to the usage cases of suspend_again; chargers and temperature sensors are mentioned so far. With suspend_again callback registered at struct platform_suspend_ops suspend_ops in kernel/power/suspend.c with suspend_set_ops by the platform, the suspend framework tries to enter suspend again by looping suspend_enter() if suspend_again has returned true and there has been no errors in the suspending sequence or pending wakeups (by pm_wakeup_pending). Tested at Exynos4-NURI. [rjw: Fixed up kerneldoc comment for suspend_enter().] Signed-off-by: MyungJoo Ham Signed-off-by: Kyungmin Park Acked-by: Pavel Machek Signed-off-by: Rafael J. Wysocki

PM / Hibernate: Introduce CONFIG_HIBERNATE_CALLBACKS

2011-04-11T20:54:42Z

Xen save/restore is going to use hibernate device callbacks for quiescing devices and putting them back to normal operations and it would need to select CONFIG_HIBERNATION for this purpose. However, that also would cause the hibernate interfaces for user space to be enabled, which might confuse user space, because the Xen kernels don't support hibernation. Moreover, it would be wasteful, as it would make the Xen kernels include a substantial amount of code that they would never use. To address this issue introduce new power management Kconfig option CONFIG_HIBERNATE_CALLBACKS, such that it will only select the code that is necessary for the hibernate device callbacks to work and make CONFIG_HIBERNATION select it. Then, Xen save/restore will be able to select CONFIG_HIBERNATE_CALLBACKS without dragging the entire hibernate code along with it. Signed-off-by: Rafael J. Wysocki Tested-by: Shriram Rajagopalan