linux-toradex.git/kernel/power/main.c, branch v3.0.16

PM / Hibernate: Add sysfs knob to control size of memory for drivers

2011-05-17T21:19:19+00:00

Martin reports that on his system hibernation occasionally fails due
to the lack of memory, because the radeon driver apparently allocates
too much of it during the device freeze stage.  It turns out that the
amount of memory allocated by radeon during hibernation (and
presumably during system suspend too) depends on the utilization of
the GPU (e.g. hibernating while there are two KDE 4 sessions with
compositing enabled causes radeon to allocate more memory than for
one KDE 4 session).

In principle it should be possible to use image_size to make the
memory preallocation mechanism free enough memory for the radeon
driver, but in practice it is not easy to guess the right value
because of the way the preallocation code uses image_size.  For this
reason, it seems reasonable to allow users to control the amount of
memory reserved for driver allocations made after the hibernate
preallocation, which currently is constant and amounts to 1 MB.

Introduce a new sysfs file, /sys/power/reserved_size, whose value
will be used as the amount of memory to reserve for the
post-preallocation reservations made by device drivers, in bytes.
For backwards compatibility, set its default (and initial) value to
the currently used number (1 MB).

References: https://bugzilla.kernel.org/show_bug.cgi?id=34102
Reported-and-tested-by: Martin Steigerwald 
Signed-off-by: Rafael J. Wysocki

Fix common misspellings

2011-03-31T14:26:23+00:00

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi

PM: Drop pm_flags that is not necessary

2011-03-14T23:43:16+00:00

The variable pm_flags is used to prevent APM from being enabled
along with ACPI, which would lead to problems.  However, acpi_init()
is always called before apm_init() and after acpi_init() has
returned, it is known whether or not ACPI will be used.  Namely, if
acpi_disabled is not set after acpi_init() has returned, this means
that ACPI is enabled.  Thus, it is sufficient to check acpi_disabled
in apm_init() to prevent APM from being enabled in parallel with
ACPI.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Len Brown

PM / ACPI: Remove references to pm_flags from bus.c

2011-03-14T23:43:15+00:00

If direct references to pm_flags are removed from drivers/acpi/bus.c,
CONFIG_ACPI will not need to depend on CONFIG_PM any more.  Make that
happen.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Len Brown

workqueue, freezer: unify spelling of 'freeze' + 'able' to 'freezable'

2011-02-16T16:48:59+00:00

There are two spellings in use for 'freeze' + 'able' - 'freezable' and
'freezeable'.  The former is the more prominent one.  The latter is
mostly used by workqueue and in a few other odd places.  Unify the
spelling to 'freezable'.

Signed-off-by: Tejun Heo 
Reported-by: Alan Stern 
Acked-by: "Rafael J. Wysocki" 
Acked-by: Greg Kroah-Hartman 
Acked-by: Dmitry Torokhov 
Cc: David Woodhouse 
Cc: Alex Dubov 
Cc: "David S. Miller" 
Cc: Steven Whitehouse

PM: Add sysfs attr for rechecking dev hash from PM trace

2010-10-16T23:57:50+00:00

If the device which fails to resume is part of a loadable kernel module
it won't be checked at startup against the magic number stored in the
RTC.

Add a read-only sysfs attribute /sys/power/pm_trace_dev_match which
contains a list of newline separated devices (usually just the one)
which currently match the last magic number. This allows the device
which is failing to resume to be found after the modules are loaded
again.

Signed-off-by: James Hogan 
Signed-off-by: Rafael J. Wysocki

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

2010-10-16T23:57:43+00:00

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 / Hibernate: Make default image size depend on total RAM size

2010-10-16T23:57:43+00:00

The default hibernation image size is currently hard coded and euqal
to 500 MB, which is not a reasonable default on many contemporary
systems.  Make it equal 2/5 of the total RAM size (this is slightly
below the maximum, i.e. 1/2 of the total RAM size, and seems to be
generally suitable).

Signed-off-by: Rafael J. Wysocki 
Tested-by: M. Vefa Bicakci

PM / Runtime: Use alloc_workqueue() for creating the PM workqueue

2010-10-16T23:57:42+00:00

Although we need the PM workqueue to be freezable, we don't need it
to be singlethread.  Also, the number of concurrent work items
running on a single CPU need not be constrained.  For these reasons
use alloc_workqueue() directly, with suitable arguments, instead of
create_freezeable_workqueue(), to create the runtime PM workqueue.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Tejun Heo

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