This patch (as1445) fixes a bug in the runtime PM core left over from
the addition of the no_callbacks flag.  If this flag is set then it is
possible for rpm_suspend() to be called in_interrupt, so when
releasing spinlocks it's important not to re-enable interrupts.

To avoid an unnecessary save-and-restore of the interrupt flag, the
patch also inlines a pm_request_idle() call.

This fixes Bugzilla #27482.

(The offending code was added in 2.6.37, so it's not necessary to apply
this to any earlier stable kernels.)

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: tim blechmann <tim@klingt.org>
CC: <stable@kernel.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

This patch (as1431c) makes the synchronous runtime-PM interface
suitable for use in interrupt handlers.  Subsystems can call the new
pm_runtime_irq_safe() function to tell the PM core that a device's
runtime_suspend and runtime_resume callbacks should be invoked with
interrupts disabled and the spinlock held.  This permits the
pm_runtime_get_sync() and the new pm_runtime_put_sync_suspend()
routines to be called from within interrupt handlers.

When a device is declared irq-safe in this way, the PM core increments
the parent's usage count, so the parent will never be runtime
suspended.  This prevents difficult situations in which an irq-safe
device can't resume because it is forced to wait for its non-irq-safe
parent.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

GCC version 4.5.1 gives the following warning:

drivers/base/power/runtime.c: In function ‘rpm_check_suspend_allowed’:
drivers/base/power/runtime.c:146:25: warning: comparison between ‘enum dpm_state’ and ‘enum rpm_status’

which seems to be a typo in that dev->power.runtime_status
should be compared instead of dev->power.status.

Signed-off-by: Kevin Winchester <kjwinchester@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

For device with no_callbacks flag set, its power lock and its parent's
power lock may be held nestedly in rpm_resume, so we should take
spin_lock_nested(lock, SINGLE_DEPTH_NESTING) to acquire parent power lock
to avoid lockdep warning.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

If runtime suspend of a device fails returning -EAGAIN or -EBUSY,
which means that it's safe to try to suspend it again, the PM core
runs the runtime idle helper function for it.  Unfortunately this may
lead to problems, for example for PCI devices whose drivers don't
implement the ->runtime_idle() callback, because in that case the
PCI bus type's ->runtime_idle() always calls pm_runtime_suspend()
for the given device.  Then, if there's an automatic idle
notification after the driver's ->runtime_suspend() returning -EAGAIN
or -EBUSY, it will make the suspend happen again possibly causing a
busy loop to appear.  To avoid that, remove the idle notification
after failing runtime suspend of a device altogether and let the
callers of pm_runtime_suspend() repeat the operation if need be.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Alan Stern <stern@rowland.harvard.edu>

Reduce code duplication in rpm_idle(), rpm_suspend() and rpm_resume()
by using local pointers to store callback addresses and moving some
duplicated code into a separate function.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>

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 <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

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 <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

This patch (as1424) combines the various public entry points for the
runtime PM routines into three simple functions: one for idle, one for
suspend, and one for resume.  A new bitflag specifies whether or not
to increment or decrement the usage_count field.

The new entry points are named __pm_runtime_idle,
__pm_runtime_suspend, and __pm_runtime_resume, to reflect that they
are trampolines.  Simultaneously, the corresponding internal routines
are renamed to rpm_idle, rpm_suspend, and rpm_resume.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

This patch (as1423) merges the asynchronous routines
__pm_request_idle(), __pm_request_suspend(), and __pm_request_resume()
with their synchronous counterparts.  The RPM_ASYNC bitflag argument
serves to indicate what sort of operation to perform.

In the course of performing this merger, it became apparent that the
various functions don't all behave consistenly with regard to error
reporting and cancellation of outstanding requests.  A new routine,
rpm_check_suspend_allowed(), was written to centralize much of the
testing, and the other functions were revised to follow a simple
algorithm:

	If the operation is disallowed because of the device's
	settings or current state, return an error.

	Cancel pending or scheduled requests of lower priority.

	Schedule, queue, or perform the desired operation.

A few special cases and exceptions are noted in comments.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>