linux-stable.git/drivers/base/power/sysfs.c, branch linux-2.6.36.y

PM / Runtime: Add runtime PM statistics (v3)

2010-07-19T00:01:06+00:00

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)

2010-07-19T00:00:36+00:00

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

2010-07-18T23:58:48+00:00

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

2010-05-10T21:08:17+00:00

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

2010-02-26T19:39:10+00:00

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

PM / Runtime: Add sysfs switch for disabling device run-time PM

2010-02-26T19:39:08+00:00

Add new device sysfs attribute, power/control, allowing the user
space to block the run-time power management of the devices.  If this
attribute is set to "on", the driver of the device won't be able to power
manage it at run time (without breaking the rules) and the device will
always be in the full power state (except when the entire system goes
into a sleep state).

Signed-off-by: Rafael J. Wysocki 
Acked-by: Alan Stern

PCI ACPI: Rework PCI handling of wake-up

2008-07-07T23:26:28+00:00

* Introduce function acpi_pm_device_sleep_wake() for enabling and
  disabling the system wake-up capability of devices that are power
  manageable by ACPI.

* Introduce function acpi_bus_can_wakeup() allowing other (dependent)
  subsystems to check if ACPI is able to enable the system wake-up
  capability of given device.

* Introduce callback .sleep_wake() in struct pci_platform_pm_ops and
  for the ACPI PCI 'driver' make it use acpi_pm_device_sleep_wake().

* Introduce callback .can_wakeup() in struct pci_platform_pm_ops and
  for the ACPI 'driver' make it use acpi_bus_can_wakeup().

* Move the PME# handlig code out of pci_enable_wake() and split it
  into two functions, pci_pme_capable() and pci_pme_active(),
  allowing the caller to check if given device is capable of
  generating PME# from given power state and to enable/disable the
  device's PME# functionality, respectively.

* Modify pci_enable_wake() to use the new ACPI callbacks and the new
  PME#-related functions.

* Drop the generic .platform_enable_wakeup() callback that is not
  used any more.

* Introduce device_set_wakeup_capable() that will set the
  power.can_wakeup flag of given device.

* Rework PCI device PM initialization so that, if given device is
  capable of generating wake-up events, either natively through the
  PME# mechanism, or with the help of the platform, its
  power.can_wakeup flag is set and its power.should_wakeup flag is
  unset as appropriate.

* Make ACPI set the power.can_wakeup flag for devices found to be
  wake-up capable by it.

* Make the ACPI wake-up code enable/disable GPEs for devices that
  have the wakeup.flags.prepared flag set (which means that their
  wake-up power has been enabled).

Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Jesse Barnes

PM: Make wakeup flags available whenever CONFIG_PM is set

2008-04-20T02:10:25+00:00

The various wakeup flags and their accessor macros in struct
dev_pm_info should be available whenever CONFIG_PM is enabled, not
just when CONFIG_PM_SLEEP is on.  Otherwise remote wakeup won't always
be configurable for runtime power management.  This patch (as1056b)
fixes the oversight.

David Brownell adds:
	More accurately, fixes the "regression" ... as noted sometime
	last summer, after 296699de6bdc717189a331ab6bbe90e05c94db06
	introduced CONFIG_SUSPEND.  But that didn't make the regression
	list for that kernel, ergo the delay in fixing it.

[rjw: rebased]

Signed-off-by: Alan Stern 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

PM: Remove deprecated sysfs files

2007-07-18T22:49:49+00:00

This patch (as932) removes the deprecated sysfs .../power/state
attribute files.

Signed-off-by: Alan Stern 
Acked-by: Pavel Machek 
Signed-off-by: Greg Kroah-Hartman

PM: add kconfig option for deprecated .../power/state files

2006-09-26T04:08:37+00:00

Add a new PM_SYSFS_DEPRECATED config option to control whether or
not the /sys/devices/.../power/state files are provided.  This will
make it easier to get rid of that mechanism when the time comes,
and to verify that userspace tools work right without it.

Signed-off-by: David Brownell 
Acked-by: Pavel Machek 
Signed-off-by: Greg Kroah-Hartman