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2012-07-03PM / Documentation: fix typos in power management descriptionOskar Schirmer1-4/+5
Just two missing characters. Signed-off-by: Oskar Schirmer <oskar@scara.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2012-01-29PM / Sleep: Introduce "late suspend" and "early resume" of devicesRafael J. Wysocki1-32/+61
The current device suspend/resume phases during system-wide power transitions appear to be insufficient for some platforms that want to use the same callback routines for saving device states and related operations during runtime suspend/resume as well as during system suspend/resume. In principle, they could point their .suspend_noirq() and .resume_noirq() to the same callback routines as their .runtime_suspend() and .runtime_resume(), respectively, but at least some of them require device interrupts to be enabled while the code in those routines is running. It also makes sense to have device suspend-resume callbacks that will be executed with runtime PM disabled and with device interrupts enabled in case someone needs to run some special code in that context during system-wide power transitions. Apart from this, .suspend_noirq() and .resume_noirq() were introduced as a workaround for drivers using shared interrupts and failing to prevent their interrupt handlers from accessing suspended hardware. It appears to be better not to use them for other porposes, or we may have to deal with some serious confusion (which seems to be happening already). For the above reasons, introduce new device suspend/resume phases, "late suspend" and "early resume" (and analogously for hibernation) whose callback will be executed with runtime PM disabled and with device interrupts enabled and whose callback pointers generally may point to runtime suspend/resume routines. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Reviewed-by: Kevin Hilman <khilman@ti.com>
2011-12-21PM: Run the driver callback directly if the subsystem one is not thereRafael J. Wysocki1-16/+21
Make the PM core execute driver PM callbacks directly if the corresponding subsystem callbacks are not present. There are three reasons for doing that. First, it reflects the behavior of drivers/base/dd.c:really_probe() that runs the driver's .probe() callback directly if the bus type's one is not defined, so this change will remove one arbitrary difference between the PM core and the remaining parts of the driver core. Second, it will allow some subsystems, whose PM callbacks don't do anything except for executing driver callbacks, to be simplified quite a bit by removing those "forward-only" callbacks. Finally, it will allow us to remove one level of indirection in the system suspend and resume code paths where it is not necessary, which is going to lead to less debug noise with initcall_debug passed in the kernel command line (messages won't be printed for driverless devices whose subsystems don't provide PM callbacks among other things). Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-11-28PM / Sleep: Update documentation related to system wakeupRafael J. Wysocki1-22/+38
The system wakeup section of Documentation/power/devices.txt is outdated, so make it agree with the current code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-11-28PM / Sleep: Correct inaccurate information in devices.txtRafael J. Wysocki1-4/+3
The documentation file Documentation/power/devices.txt contains some information that isn't correct any more due to code modifications made after that file had been created (or updated last time). Fix this. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-11-28PM / Domains: Document how PM domains are used by the PM coreRafael J. Wysocki1-15/+27
The current power management documentation in Documentation/power/ either doesn't cover PM domains at all, or gives inaccurate information about them, so update the relevant files in there to follow the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-10-16PM / Hibernate: Freeze kernel threads after preallocating memoryRafael J. Wysocki1-4/+0
There is a problem with the current ordering of hibernate code which leads to deadlocks in some filesystems' memory shrinkers. Namely, some filesystems use freezable kernel threads that are inactive when the hibernate memory preallocation is carried out. Those same filesystems use memory shrinkers that may be triggered by the hibernate memory preallocation. If those memory shrinkers wait for the frozen kernel threads, the hibernate process deadlocks (this happens with XFS, for one example). Apparently, it is not technically viable to redesign the filesystems in question to avoid the situation described above, so the only possible solution of this issue is to defer the freezing of kernel threads until the hibernate memory preallocation is done, which is implemented by this change. Unfortunately, this requires the memory preallocation to be done before the "prepare" stage of device freeze, so after this change the only way drivers can allocate additional memory for their freeze routines in a clean way is to use PM notifiers. Reported-by: Christoph <cr2005@u-club.de> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-10-16PM: Update the policy on default wakeup settingsAlan Stern1-1/+3
This patch (as1485) documents a change to the kernel's default wakeup policy. Devices that forward wakeup requests between buses should be enabled for wakeup by default. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-07-02PM / Runtime: Update documentation of interactions with system sleepRafael J. Wysocki1-3/+3
The documents describing the interactions between runtime PM and system sleep generally refer to the model in which the system sleep state is entered through a global firmware or hardware operation. As a result, some recommendations given in there are not entirely suitable for systems in which this is not the case. Update the documentation to take the existence of those systems into account. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Reviewed-by: Kevin Hilman <khilman@ti.com>
2011-07-02PM / Domains: Rename struct dev_power_domain to struct dev_pm_domainRafael J. Wysocki1-4/+4
The naming convention used by commit 7538e3db6e015e890825fbd9f86599b (PM: Add support for device power domains), which introduced the struct dev_power_domain type for representing device power domains, evidently confuses some developers who tend to think that objects of this type must correspond to "power domains" as defined by hardware, which is not the case. Namely, at the kernel level, a struct dev_power_domain object can represent arbitrary set of devices that are mutually dependent power management-wise and need not belong to one hardware power domain. To avoid that confusion, rename struct dev_power_domain to struct dev_pm_domain and rename the related pointers in struct device and struct pm_clk_notifier_block from pwr_domain to pm_domain. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Kevin Hilman <khilman@ti.com>
2011-06-21PM / Domains: Update documentationRafael J. Wysocki1-27/+14
Commit 4d27e9dcff00a6425d779b065ec8892e4f391661 (PM: Make power domain callbacks take precedence over subsystem ones) forgot to update the device power management documentation to take changes made by it into account. Correct that mistake. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-06-21PM: Update documentation regarding sysdevsRafael J. Wysocki1-26/+0
The part of Documentation/power/devices.txt regarding sysdevs is not valid any more after commit 2e711c04dbbf7a7732a3f7073b1fc285d12b369d (PM: Remove sysdev suspend, resume and shutdown operations), so remove it. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17PM: Allow drivers to allocate memory from .prepare() callbacks safelyRafael J. Wysocki1-5/+9
If device drivers allocate substantial amounts of memory (above 1 MB) in their hibernate .freeze() callbacks (or in their legacy suspend callbcks during hibernation), the subsequent creation of hibernate image may fail due to the lack of memory. This is the case, because the drivers' .freeze() callbacks are executed after the hibernate memory preallocation has been carried out and the preallocated amount of memory may be too small to cover the new driver allocations. Unfortunately, the drivers' .prepare() callbacks also are executed after the hibernate memory preallocation has completed, so they are not suitable for allocating additional memory either. Thus the only way a driver can safely allocate memory during hibernation is to use a hibernate/suspend notifier. However, the notifiers are called before the freezing of user space and the drivers wanting to use them for allocating additional memory may not know how much memory needs to be allocated at that point. To let device drivers overcome this difficulty rework the hibernation sequence so that the memory preallocation is carried out after the drivers' .prepare() callbacks have been executed, so that the .prepare() callbacks can be used for allocating additional memory to be used by the drivers' .freeze() callbacks. Update documentation to match the new behavior of the code. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-03-31Fix common misspellingsLucas De Marchi1-1/+1
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-15PM: Make system-wide PM and runtime PM treat subsystems consistentlyRafael J. Wysocki1-17/+12
The code handling system-wide power transitions (eg. suspend-to-RAM) can in theory execute callbacks provided by the device's bus type, device type and class in each phase of the power transition. In turn, the runtime PM core code only calls one of those callbacks at a time, preferring bus type callbacks to device type or class callbacks and device type callbacks to class callbacks. It seems reasonable to make them both behave in the same way in that respect. Moreover, even though a device may belong to two subsystems (eg. bus type and device class) simultaneously, in practice power management callbacks for system-wide power transitions are always provided by only one of them (ie. if the bus type callbacks are defined, the device class ones are not and vice versa). Thus it is possible to modify the code handling system-wide power transitions so that it follows the core runtime PM code (ie. treats the subsystem callbacks as mutually exclusive). On the other hand, the core runtime PM code will choose to execute, for example, a runtime suspend callback provided by the device type even if the bus type's struct dev_pm_ops object exists, but the runtime_suspend pointer in it happens to be NULL. This is confusing, because it may lead to the execution of callbacks from different subsystems during different operations (eg. the bus type suspend callback may be executed during runtime suspend of the device, while the device type callback will be executed during system suspend). Make all of the power management code treat subsystem callbacks in a consistent way, such that: (1) If the device's type is defined (eg. dev->type is not NULL) and its pm pointer is not NULL, the callbacks from dev->type->pm will be used. (2) If dev->type is NULL or dev->type->pm is NULL, but the device's class is defined (eg. dev->class is not NULL) and its pm pointer is not NULL, the callbacks from dev->class->pm will be used. (3) If dev->type is NULL or dev->type->pm is NULL and dev->class is NULL or dev->class->pm is NULL, the callbacks from dev->bus->pm will be used provided that both dev->bus and dev->bus->pm are not NULL. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Kevin Hilman <khilman@ti.com> Reasoning-sounds-sane-to: Grant Likely <grant.likely@secretlab.ca> Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-03-15PM: Add support for device power domainsRafael J. Wysocki1-1/+44
The platform bus type is often used to handle Systems-on-a-Chip (SoC) where all devices are represented by objects of type struct platform_device. In those cases the same "platform" device driver may be used with multiple different system configurations, but the actions needed to put the devices it handles into a low-power state and back into the full-power state may depend on the design of the given SoC. The driver, however, cannot possibly include all the information necessary for the power management of its device on all the systems it is used with. Moreover, the device hierarchy in its current form also is not suitable for representing this kind of information. The patch below attempts to address this problem by introducing objects of type struct dev_power_domain that can be used for representing power domains within a SoC. Every struct dev_power_domain object provides a sets of device power management callbacks that can be used to perform what's needed for device power management in addition to the operations carried out by the device's driver and subsystem. Namely, if a struct dev_power_domain object is pointed to by the pwr_domain field in a struct device, the callbacks provided by its ops member will be executed in addition to the corresponding callbacks provided by the device's subsystem and driver during all power transitions. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Tested-and-acked-by: Kevin Hilman <khilman@ti.com>
2011-03-15PM: Do not create wakeup sysfs files for devices that cannot wake upRafael J. Wysocki1-10/+10
Currently, wakeup sysfs attributes are created for all devices, regardless of whether or not they are wakeup-capable. This is excessive and complicates wakeup device identification from user space (i.e. to identify wakeup-capable devices user space has to read /sys/devices/.../power/wakeup for all devices and see if they are not empty). Fix this issue by avoiding to create wakeup sysfs files for devices that cannot wake up the system from sleep states (i.e. whose power.can_wakeup flags are unset during registration) and modify device_set_wakeup_capable() so that it adds (or removes) the relevant sysfs attributes if a device's wakeup capability status is changed. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2010-05-10PM: Improve device power management documentAlan Stern1-428/+383
Improve the device power management document after it's been updated by the previous patch. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2010-05-10PM: Update device power management documentRafael J. Wysocki1-267/+431
The device PM document, Documentation/power/devices.txt, is badly outdated and requires total rework to fit the current design of the PM framework. Make it more up to date. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Reviewed-by: Randy Dunlap <randy.dunlap@oracle.com>
2009-06-12PM: Remove bus_type suspend_late()/resume_early() V2Magnus Damm1-29/+5
Remove the ->suspend_late() and ->resume_early() callbacks from struct bus_type V2. These callbacks are legacy stuff at this point and since there seem to be no in-tree users we may as well remove them. New users should use dev_pm_ops. Signed-off-by: Magnus Damm <damm@igel.co.jp> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2008-04-19PM: Handle device registrations during suspend/resumeRafael J. Wysocki1-0/+5
Modify the PM core to protect its data structures, specifically the dpm_active list, from being corrupted if a child of the currently suspending device is registered concurrently with its ->suspend() callback. In that case, since the new device (the child) is added to dpm_active after its parent, the PM core will attempt to suspend it after the parent, which is wrong. Introduce a new member of struct dev_pm_info, called 'sleeping', and use it to check if the parent of the device being added to dpm_active has been suspended, in which case the device registration fails. Also, use 'sleeping' for checking if the ordering of devices on dpm_active is correct. Introduce variable 'all_sleeping' that will be set to 'true' once all devices have been suspended and make new device registrations fail until 'all_sleeping' is reset to 'false', in order to avoid having unsuspended devices around while the system is going into a sleep state. Remove pm_sleep_rwsem which is not necessary any more. Special thanks to Alan Stern for discussions and suggestions that lead to the creation of this patch. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-02-23PM: Introduce PM_EVENT_HIBERNATE callback stateRafael J. Wysocki1-5/+8
During the last step of hibernation in the "platform" mode (with the help of ACPI) we use the suspend code, including the devices' ->suspend() methods, to prepare the system for entering the ACPI S4 system sleep state. But at least for some devices the operations performed by the ->suspend() callback in that case must be different from its operations during regular suspend. For this reason, introduce the new PM event type PM_EVENT_HIBERNATE and pass it to the device drivers' ->suspend() methods during the last phase of hibernation, so that they can distinguish this case and handle it as appropriate. Modify the drivers that handle PM_EVENT_SUSPEND in a special way and need to handle PM_EVENT_HIBERNATE in the same way. These changes are necessary to fix a hibernation regression related to the i915 driver (ref. http://lkml.org/lkml/2008/2/22/488). Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Tested-by: Jeff Chua <jeff.chua.linux@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-01PM: Remove obsolete /sys/devices/.../power/state docsDavid Brownell1-49/+0
The /sys/devices/.../power/state files have been gone for a while now, but I just noticed some documentation that still refers to them. (Fortunately described as DEPRECATED and WILL REMOVE). Time to remove that obsolete documentation too ... Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Len Brown <len.brown@intel.com>
2006-09-25updated Documentation/power/devices.txtDavid Brownell1-190/+535
This turned into a rewrite of Documentation/power/devices.txt: - Provide more of the "big picture" - Fixup some of the horribly ancient/obsolete description of device suspend() semantics; lots of text just got deleted. - Add a decent description of PM_EVENT_* codes, including the new PRETHAW code needed in some swsusp scenarios. - Describe the new PM factorization from Linus: * class suspend, current suspend, then suspend_late * NOT suspend_prepare, it wasn't really usable * resume_early, current resume, class resume. - Updates power/state docs to be correct, and deprecate its usage except for driver testing. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-06-21[PATCH] remove duplication from Documentation/power/devices.txtDavid Brownell1-90/+0
Remove a chunk of duplicated documentation text. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-05-17[PATCH] Driver Core: remove driver model detach_stateDavid Brownell1-21/+0
The driver model has a "detach_state" mechanism that: - Has never been used by any in-kernel drive; - Is superfluous, since driver remove() methods can do the same thing; - Became buggy when the suspend() parameter changed semantics and type; - Could self-deadlock when called from certain suspend contexts; - Is effectively wasted documentation, object code, and headspace. This removes that "detach_state" mechanism; net code shrink, as well as a per-device saving in the driver model and sysfs. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-04-16Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds1-0/+319
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!