linux/drivers/base/power/sysfs.c, branch v3.0.85

PM / Wakeup: Fix build warning related to the "wakeup" sysfs file

2011-05-17T21:19:18Z

The "wakeup" device sysfs file is only created if CONFIG_PM_SLEEP is set, so put it under CONFIG_PM_SLEEP and make a build warning related to it go away. Signed-off-by: Rafael J. Wysocki Acked-by: Greg Kroah-Hartman

PM: Do not create wakeup sysfs files for devices that cannot wake up

2011-03-14T23:43:14Z

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

PM / Runtime: Implement autosuspend support

2010-10-16T23:57:48Z

This patch (as1427) implements the "autosuspend" facility for runtime PM. A few new fields are added to the dev_pm_info structure and several new PM helper functions are defined, for telling the PM core whether or not a device uses autosuspend, for setting the autosuspend delay, and for marking periods of device activity. Drivers that do not want to use autosuspend can continue using the same helper functions as before; their behavior will not change. In addition, drivers supporting autosuspend can also call the old helper functions to get the old behavior. The details are all explained in Documentation/power/runtime_pm.txt and Documentation/ABI/testing/sysfs-devices-power. Signed-off-by: Alan Stern Signed-off-by: Rafael J. Wysocki

PM / Runtime: Add no_callbacks flag

2010-10-16T23:57:47Z

Some devices, such as USB interfaces, cannot be power-managed independently of their parents, i.e., they cannot be put in low power while the parent remains at full power. This patch (as1425) creates a new "no_callbacks" flag, which tells the PM core not to invoke the runtime-PM callback routines for the such devices but instead to assume that the callbacks always succeed. In addition, the non-debugging runtime-PM sysfs attributes for the devices are removed, since they are pretty much meaningless. The advantage of this scheme comes not so much from avoiding the callbacks themselves, but rather from the fact that without the need for a process context in which to run the callbacks, more work can be done in interrupt context. Signed-off-by: Alan Stern Signed-off-by: Rafael J. Wysocki

PM / Wakeup: Introduce wakeup source objects and event statistics (v3)

2010-10-16T23:57:43Z

Introduce struct wakeup_source for representing system wakeup sources within the kernel and for collecting statistics related to them. Make the recently introduced helper functions pm_wakeup_event(), pm_stay_awake() and pm_relax() use struct wakeup_source objects internally, so that wakeup statistics associated with wakeup devices can be collected and reported in a consistent way (the definition of pm_relax() is changed, which is harmless, because this function is not called directly by anyone yet). Introduce new wakeup-related sysfs device attributes in /sys/devices/.../power for reporting the device wakeup statistics. Change the global wakeup events counters event_count and events_in_progress into atomic variables, so that it is not necessary to acquire a global spinlock in pm_wakeup_event(), pm_stay_awake() and pm_relax(), which should allow us to avoid lock contention in these functions on SMP systems with many wakeup devices. Signed-off-by: Rafael J. Wysocki Acked-by: Greg Kroah-Hartman

PM / Runtime: Add runtime PM statistics (v3)

2010-07-19T00:01:06Z

In order for PowerTOP to be able to report how well the new runtime PM is working for the various drivers, the kernel needs to export some basic statistics in sysfs. This patch adds two sysfs files in the runtime PM domain that expose the total time a device has been active, and the time a device has been suspended. With this PowerTOP can compute the activity percentage Active %age = 100 * (delta active) / (delta active + delta suspended) and present the information to the user. I've written the PowerTOP code (slated for version 1.12) already, and the output looks like this: Runtime Device Power Management statistics Active Device name 10.0% 06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller [version 2: fix stat update bugs noticed by Alan Stern] [version 3: rebase to -next and move the sysfs declaration] Signed-off-by: Arjan van de Ven Signed-off-by: Rafael J. Wysocki

PM / Runtime: Make runtime_status attribute not debug-only (v. 2)

2010-07-19T00:00:36Z

This patch (as1404b) makes the runtime_status sysfs attribute available even in the absence of CONFIG_PM_ADVANCED_DEBUG, and it changes the routine to display "unsupported" when runtime PM is disabled for a device. Although not strictly 100% accurate, this will almost always be correct. Signed-off-by: Alan Stern Acked-by: Dominik Brodowski Signed-off-by: Rafael J. Wysocki

PM: Make it possible to avoid races between wakeup and system sleep

2010-07-18T23:58:48Z

One of the arguments during the suspend blockers discussion was that the mainline kernel didn't contain any mechanisms making it possible to avoid races between wakeup and system suspend. Generally, there are two problems in that area. First, if a wakeup event occurs exactly when /sys/power/state is being written to, it may be delivered to user space right before the freezer kicks in, so the user space consumer of the event may not be able to process it before the system is suspended. Second, if a wakeup event occurs after user space has been frozen, it is not generally guaranteed that the ongoing transition of the system into a sleep state will be aborted. To address these issues introduce a new global sysfs attribute, /sys/power/wakeup_count, associated with a running counter of wakeup events and three helper functions, pm_stay_awake(), pm_relax(), and pm_wakeup_event(), that may be used by kernel subsystems to control the behavior of this attribute and to request the PM core to abort system transitions into a sleep state already in progress. The /sys/power/wakeup_count file may be read from or written to by user space. Reads will always succeed (unless interrupted by a signal) and return the current value of the wakeup events counter. Writes, however, will only succeed if the written number is equal to the current value of the wakeup events counter. If a write is successful, it will cause the kernel to save the current value of the wakeup events counter and to abort the subsequent system transition into a sleep state if any wakeup events are reported after the write has returned. [The assumption is that before writing to /sys/power/state user space will first read from /sys/power/wakeup_count. Next, user space consumers of wakeup events will have a chance to acknowledge or veto the upcoming system transition to a sleep state. Finally, if the transition is allowed to proceed, /sys/power/wakeup_count will be written to and if that succeeds, /sys/power/state will be written to as well. Still, if any wakeup events are reported to the PM core by kernel subsystems after that point, the transition will be aborted.] Additionally, put a wakeup events counter into struct dev_pm_info and make these per-device wakeup event counters available via sysfs, so that it's possible to check the activity of various wakeup event sources within the kernel. To illustrate how subsystems can use pm_wakeup_event(), make the low-level PCI runtime PM wakeup-handling code use it. Signed-off-by: Rafael J. Wysocki Acked-by: Jesse Barnes Acked-by: Greg Kroah-Hartman Acked-by: markgross Reviewed-by: Alan Stern

PM / Runtime: Add sysfs debug files

2010-05-10T21:08:17Z

Add a few sysfs files relating to runtime power management for advanced debug purposes: runtime_enabled: is runtime PM enabled for this device? States are "enabled", "disabled", "forbidden" or a combination of the latter two. runtime_status: what state is the device in currently? E.g., it reports "suspended" for runtime-suspended devices, and "active" for active devices. NOTE: if runtime_enabled returns "disabled", the value of this file may not reflect its physical state. runtime_usage: the runtime PM usage count of a device runtime_active_kids: the runtime PM children usage count of a device, or 0 if the ignore_children flag is set. Also, CONFIG_PM_SLEEP_ADVANCED_DEBUG is not defined in any Kconfig file, so replace it with CONFIG_PM_ADVANCED_DEBUG. Signed-off-by: Dominik Brodowski Acked-by: Alan Stern Signed-off-by: Rafael J. Wysocki

PM: Add facility for advanced testing of async suspend/resume

2010-02-26T19:39:10Z

Add configuration switch CONFIG_PM_ADVANCED_DEBUG for compiling in extra PM debugging/testing code allowing one to access some PM-related attributes of devices from the user space via sysfs. If CONFIG_PM_ADVANCED_DEBUG is set, add sysfs attribute power/async for every device allowing the user space to access the device's power.async_suspend flag and modify it, if desired. Signed-off-by: Rafael J. Wysocki