Cast autosuspend_delay to u64 to make sure that the full computation
of 'expires' or slack will be done in u64, even on 32bits arch.

Otherwise, any delay greater than 2^31 nsec can overflow if signed
32bits is used when converting delay from msec to nsec.

Fixes: 8234f6734c5d (PM-runtime: Switch autosuspend over to using hrtimers)
Reported-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

PM-runtime now uses the hrtimers infrastructure for autosuspend, however
comments still reference 'jiffies'.

Fixes: 8234f6734c5d (PM-runtime: Switch autosuspend over to using hrtimers)
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

PM-runtime uses the timer infrastructure for autosuspend. This implies
that the minimum time before autosuspending a device is in the range
of 1 tick included to 2 ticks excluded
 -On arm64 this means between 4ms and 8ms with default jiffies
  configuration
 -And on arm, it is between 10ms and 20ms

These values are quite high for embedded systems which sometimes want
the duration to be in the range of 1 ms.

It is possible to switch autosuspend over to using hrtimers to get
finer granularity for short durations and take advantage of slack to
retain some margins and get long timeouts with minimum wakeups.

On an arm64 platform that uses 1ms for autosuspending timeout of its
GPU, idle power is reduced by 10% with hrtimer.

The latency impact on arm64 hikey octo cores is:
 - mark_last_busy: from 1.11 us to 1.25 us
 - rpm_suspend: from 15.54 us to 15.38 us
[Only the code path of rpm_suspend() that starts hrtimer has been
measured.]

arm64 image (arm64 default defconfig) decreases by around 3KB
with following details:

$ size vmlinux-timer
   text	   data	    bss	    dec	    hex	filename
12034646	6869268	 386840	19290754	1265a82	vmlinux

$ size vmlinux-hrtimer
   text	   data	    bss	    dec	    hex	filename
12030550	6870164	 387032	19287746	1264ec2	vmlinux

The latency impact on arm 32bits snowball dual cores is :
 - mark_last_busy: from 0.31 us usec to 0.77 us
 - rpm_suspend: from 6.83 us to 6.67 usec

The increase of the image for snowball platform that I used for
testing performance impact, is neglictable (244B).

$ size vmlinux-timer
   text	   data	    bss	    dec	    hex	filename
7157961	2119580	 264120	9541661	 91981d	build-ux500/vmlinux

size vmlinux-hrtimer
   text	   data	    bss	    dec	    hex	filename
7157773	2119884	 264248	9541905	 919911	vmlinux-hrtimer

And arm 32bits image (multi_v7_defconfig) increases by around 1.7KB
with following details:

$ size vmlinux-timer
   text	   data	    bss	    dec	    hex	filename
13304443	6803420	 402768	20510631	138f7a7	vmlinux

$ size vmlinux-hrtimer
   text	   data	    bss	    dec	    hex	filename
13304299	6805276	 402768	20512343	138fe57	vmlinux

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Revert commit 1e8378619841 (PM / runtime: Fixup reference counting of
device link suppliers at probe), as it has introduced a regression
and the condition it was designed to address should be covered by the
existing code.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

In the case consumer device is runtime resumed, while the link to the
supplier is removed, the earlier call to pm_runtime_get_sync() made from
rpm_get_suppliers() does not get properly balanced with a corresponding
call to pm_runtime_put(). This leads to that suppliers remains to be
runtime resumed forever, while they don't need to.

Let's fix the behaviour by calling rpm_put_suppliers() when dropping a
device link. Not that, since rpm_put_suppliers() checks the
link->rpm_active flag, we can correctly avoid to call pm_runtime_put() in
cases when we shouldn't.

Reported-by: Todor Tomov <todor.tomov@linaro.org>
Fixes: 21d5c57b3726 (PM / runtime: Use device links)
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

In the driver core, before it invokes really_probe() it runtime resumes the
suppliers for the device via calling pm_runtime_get_suppliers(), which also
increases the runtime PM usage count for each of the available supplier.

This makes sense, as to be able to allow the consumer device to be probed
by its driver. However, if the driver decides to add a new supplier link
during ->probe(), hence updating the list of suppliers, the following call
to pm_runtime_put_suppliers(), invoked after really_probe() in the driver
core, we get into trouble.

More precisely, pm_runtime_put() gets called also for the new supplier(s),
which is wrong as the driver core, didn't trigger pm_runtime_get_sync() to
be called for it in the first place. In other words, the new supplier may
be runtime suspended even in cases when it shouldn't.

Fix this behaviour, by runtime resume suppliers according to the same
conditions as managed by the runtime PM core, when runtime resume callbacks
are being invoked.

Additionally, don't try to runtime suspend any of the suppliers after
really_probe(), but instead rely on that to happen via the consumer device,
when it becomes runtime suspended.

Fixes: 21d5c57b3726 (PM / runtime: Use device links)
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The pm_runtime_force_suspend|resume() helpers currently requires the device
to at some level (PM domain, bus, etc), have the ->runtime_suspend|resume()
callbacks assigned for it, else -ENOSYS is returned as an error.

However, there are no reason for this requirement, so let's simply remove
it by allowing these callbacks to be NULL.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Modify pm_runtime_need_not_resume() to make it avoid taking
power.child_count for devices with power.ignore_children which
is consistent with the runtime PM usage of these fields.

Suggested-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

One of the limitations of pm_runtime_force_suspend/resume() is that
if a parent driver wants to use these functions, all of its child
drivers generally have to do that too because of the parent usage
counter manipulations necessary to get the correct state of the parent
during system-wide transitions to the working state (system resume).
However, that limitation turns out to be artificial, so remove it.

Namely, pm_runtime_force_suspend() only needs to update the children
counter of its parent (if there's is a parent) when the device can
stay in suspend after the subsequent system resume transition, as
that counter is correct already otherwise.  Now, if the parent's
children counter is not updated, it is not necessary to increment
the parent's usage counter in that case any more, as long as the
children counters of devices are checked along with their usage
counters in order to decide whether or not the devices may be left
in suspend after the subsequent system resume transition.

Accordingly, modify pm_runtime_force_suspend() to only call
pm_runtime_set_suspended() for devices whose usage and children
counters are at the "no references" level (the runtime PM status
of the device needs to be updated to "suspended" anyway in case
this function is called once again for the same device during the
transition under way), drop the parent usage counter incrementation
from it and update pm_runtime_force_resume() to compensate for these
changes.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Prevent rpm_get_suppliers() from returning an error code if runtime
PM is disabled for one or more of the supplier devices it wants to
runtime-resume, so as to make runtime PM work for devices with links
to suppliers that don't use runtime PM (such links may be created
during device enumeration even before it is known whether or not
runtime PM will be enabled for the devices in question, for example).

Fixes: 21d5c57b3726 (PM / runtime: Use device links)
Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Tested-by: Adrian Hunter <adrian.hunter@intel.com>