Merge tag 'pm-4.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management updates from Rafael Wysocki:
 "There are no real big ticket items here this time.

  The most noticeable change is probably the relocation of the OPP
  (Operating Performance Points) framework to its own directory under
  drivers/ as it has grown big enough for that. Also Viresh is now going
  to maintain it and send pull requests for it to me, so you will see
  this change in the git history going forward (but still not right
  now).

  Another noticeable set of changes is the modifications of the PM core,
  the PCI subsystem and the ACPI PM domain to allow of more integration
  between system-wide suspend/resume and runtime PM. For now it's just a
  way to avoid resuming devices from runtime suspend unnecessarily
  during system suspend (if the driver sets a flag to indicate its
  readiness for that) and in the works is an analogous mechanism to
  allow devices to stay suspended after system resume.

  In addition to that, we have some changes related to supporting
  frequency-invariant CPU utilization metrics in the scheduler and in
  the schedutil cpufreq governor on ARM and changes to add support for
  device performance states to the generic power domains (genpd)
  framework.

  The rest is mostly fixes and cleanups of various sorts.

  Specifics:

   - Relocate the OPP (Operating Performance Points) framework to its
     own directory under drivers/ and add support for power domain
     performance states to it (Viresh Kumar).

   - Modify the PM core, the PCI bus type and the ACPI PM domain to
     support power management driver flags allowing device drivers to
     specify their capabilities and preferences regarding the handling
     of devices with enabled runtime PM during system suspend/resume and
     clean up that code somewhat (Rafael Wysocki, Ulf Hansson).

   - Add frequency-invariant accounting support to the task scheduler on
     ARM and ARM64 (Dietmar Eggemann).

   - Fix PM QoS device resume latency framework to prevent "no
     restriction" requests from overriding requests with specific
     requirements and drop the confusing PM_QOS_FLAG_REMOTE_WAKEUP
     device PM QoS flag (Rafael Wysocki).

   - Drop legacy class suspend/resume operations from the PM core and
     drop legacy bus type suspend and resume callbacks from ARM/locomo
     (Rafael Wysocki).

   - Add min/max frequency support to devfreq and clean it up somewhat
     (Chanwoo Choi).

   - Rework wakeup support in the generic power domains (genpd)
     framework and update some of its users accordingly (Geert
     Uytterhoeven).

   - Convert timers in the PM core to use timer_setup() (Kees Cook).

   - Add support for exposing the SLP_S0 (Low Power S0 Idle) residency
     counter based on the LPIT ACPI table on Intel platforms (Srinivas
     Pandruvada).

   - Add per-CPU PM QoS resume latency support to the ladder cpuidle
     governor (Ramesh Thomas).

   - Fix a deadlock between the wakeup notify handler and the notifier
     removal in the ACPI core (Ville Syrjälä).

   - Fix a cpufreq schedutil governor issue causing it to use stale
     cached frequency values sometimes (Viresh Kumar).

   - Fix an issue in the system suspend core support code causing wakeup
     events detection to fail in some cases (Rajat Jain).

   - Fix the generic power domains (genpd) framework to prevent the PM
     core from using the direct-complete optimization with it as that is
     guaranteed to fail (Ulf Hansson).

   - Fix a minor issue in the cpuidle core and clean it up a bit (Gaurav
     Jindal, Nicholas Piggin).

   - Fix and clean up the intel_idle and ARM cpuidle drivers (Jason
     Baron, Len Brown, Leo Yan).

   - Fix a couple of minor issues in the OPP framework and clean it up
     (Arvind Yadav, Fabio Estevam, Sudeep Holla, Tobias Jordan).

   - Fix and clean up some cpufreq drivers and fix a minor issue in the
     cpufreq statistics code (Arvind Yadav, Bhumika Goyal, Fabio
     Estevam, Gautham Shenoy, Gustavo Silva, Marek Szyprowski, Masahiro
     Yamada, Robert Jarzmik, Zumeng Chen).

   - Fix minor issues in the system suspend and hibernation core, in
     power management documentation and in the AVS (Adaptive Voltage
     Scaling) framework (Helge Deller, Himanshu Jha, Joe Perches, Rafael
     Wysocki).

   - Fix some issues in the cpupower utility and document that Shuah
     Khan is going to maintain it going forward (Prarit Bhargava, Shuah
     Khan)"

* tag 'pm-4.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (88 commits)
  tools/power/cpupower: add libcpupower.so.0.0.1 to .gitignore
  tools/power/cpupower: Add 64 bit library detection
  intel_idle: Graceful probe failure when MWAIT is disabled
  cpufreq: schedutil: Reset cached_raw_freq when not in sync with next_freq
  freezer: Fix typo in freezable_schedule_timeout() comment
  PM / s2idle: Clear the events_check_enabled flag
  cpufreq: stats: Handle the case when trans_table goes beyond PAGE_SIZE
  cpufreq: arm_big_little: make cpufreq_arm_bL_ops structures const
  cpufreq: arm_big_little: make function arguments and structure pointer const
  cpuidle: Avoid assignment in if () argument
  cpuidle: Clean up cpuidle_enable_device() error handling a bit
  ACPI / PM: Fix acpi_pm_notifier_lock vs flush_workqueue() deadlock
  PM / Domains: Fix genpd to deal with drivers returning 1 from ->prepare()
  cpuidle: ladder: Add per CPU PM QoS resume latency support
  PM / QoS: Fix device resume latency framework
  PM / domains: Rework governor code to be more consistent
  PM / Domains: Remove gpd_dev_ops.active_wakeup() callback
  soc: rockchip: power-domain: Use GENPD_FLAG_ACTIVE_WAKEUP
  soc: mediatek: Use GENPD_FLAG_ACTIVE_WAKEUP
  ARM: shmobile: pm-rmobile: Use GENPD_FLAG_ACTIVE_WAKEUP
  ...

1 files changed, 59 insertions, 2 deletions

diff --git a/Documentation/driver-api/pm/devices.rst b/Documentation/driver-api/pm/devices.rst
index a0dc2879a152..53c1b0b06da5 100644
--- a/Documentation/driver-api/pm/devices.rst
+++ b/Documentation/driver-api/pm/devices.rst
@@ -274,7 +274,7 @@ sleep states and the hibernation state ("suspend-to-disk").  Each phase involves
 executing callbacks for every device before the next phase begins.  Not all
 buses or classes support all these callbacks and not all drivers use all the
 callbacks.  The various phases always run after tasks have been frozen and
-before they are unfrozen.  Furthermore, the ``*_noirq phases`` run at a time
+before they are unfrozen.  Furthermore, the ``*_noirq`` phases run at a time
 when IRQ handlers have been disabled (except for those marked with the
 IRQF_NO_SUSPEND flag).
 
@@ -328,7 +328,10 @@ the phases are: ``prepare``, ``suspend``, ``suspend_late``, ``suspend_noirq``.
 	After the ``->prepare`` callback method returns, no new children may be
 	registered below the device.  The method may also prepare the device or
 	driver in some way for the upcoming system power transition, but it
-	should not put the device into a low-power state.
+	should not put the device into a low-power state.  Moreover, if the
+	device supports runtime power management, the ``->prepare`` callback
+	method must not update its state in case it is necessary to resume it
+	from runtime suspend later on.
 
 	For devices supporting runtime power management, the return value of the
 	prepare callback can be used to indicate to the PM core that it may
@@ -351,11 +354,35 @@ the phases are: ``prepare``, ``suspend``, ``suspend_late``, ``suspend_noirq``.
 	is because all such devices are initially set to runtime-suspended with
 	runtime PM disabled.
 
+	This feature also can be controlled by device drivers by using the
+	``DPM_FLAG_NEVER_SKIP`` and ``DPM_FLAG_SMART_PREPARE`` driver power
+	management flags.  [Typically, they are set at the time the driver is
+	probed against the device in question by passing them to the
+	:c:func:`dev_pm_set_driver_flags` helper function.]  If the first of
+	these flags is set, the PM core will not apply the direct-complete
+	procedure described above to the given device and, consequenty, to any
+	of its ancestors.  The second flag, when set, informs the middle layer
+	code (bus types, device types, PM domains, classes) that it should take
+	the return value of the ``->prepare`` callback provided by the driver
+	into account and it may only return a positive value from its own
+	``->prepare`` callback if the driver's one also has returned a positive
+	value.
+
     2.	The ``->suspend`` methods should quiesce the device to stop it from
 	performing I/O.  They also may save the device registers and put it into
 	the appropriate low-power state, depending on the bus type the device is
 	on, and they may enable wakeup events.
 
+	However, for devices supporting runtime power management, the
+	``->suspend`` methods provided by subsystems (bus types and PM domains
+	in particular) must follow an additional rule regarding what can be done
+	to the devices before their drivers' ``->suspend`` methods are called.
+	Namely, they can only resume the devices from runtime suspend by
+	calling :c:func:`pm_runtime_resume` for them, if that is necessary, and
+	they must not update the state of the devices in any other way at that
+	time (in case the drivers need to resume the devices from runtime
+	suspend in their ``->suspend`` methods).
+
     3.	For a number of devices it is convenient to split suspend into the
 	"quiesce device" and "save device state" phases, in which cases
 	``suspend_late`` is meant to do the latter.  It is always executed after
@@ -729,6 +756,36 @@ state temporarily, for example so that its system wakeup capability can be
 disabled.  This all depends on the hardware and the design of the subsystem and
 device driver in question.
 
+If it is necessary to resume a device from runtime suspend during a system-wide
+transition into a sleep state, that can be done by calling
+:c:func:`pm_runtime_resume` for it from the ``->suspend`` callback (or its
+couterpart for transitions related to hibernation) of either the device's driver
+or a subsystem responsible for it (for example, a bus type or a PM domain).
+That is guaranteed to work by the requirement that subsystems must not change
+the state of devices (possibly except for resuming them from runtime suspend)
+from their ``->prepare`` and ``->suspend`` callbacks (or equivalent) *before*
+invoking device drivers' ``->suspend`` callbacks (or equivalent).
+
+Some bus types and PM domains have a policy to resume all devices from runtime
+suspend upfront in their ``->suspend`` callbacks, but that may not be really
+necessary if the driver of the device can cope with runtime-suspended devices.
+The driver can indicate that by setting ``DPM_FLAG_SMART_SUSPEND`` in
+:c:member:`power.driver_flags` at the probe time, by passing it to the
+:c:func:`dev_pm_set_driver_flags` helper.  That also may cause middle-layer code
+(bus types, PM domains etc.) to skip the ``->suspend_late`` and
+``->suspend_noirq`` callbacks provided by the driver if the device remains in
+runtime suspend at the beginning of the ``suspend_late`` phase of system-wide
+suspend (or in the ``poweroff_late`` phase of hibernation), when runtime PM
+has been disabled for it, under the assumption that its state should not change
+after that point until the system-wide transition is over.  If that happens, the
+driver's system-wide resume callbacks, if present, may still be invoked during
+the subsequent system-wide resume transition and the device's runtime power
+management status may be set to "active" before enabling runtime PM for it,
+so the driver must be prepared to cope with the invocation of its system-wide
+resume callbacks back-to-back with its ``->runtime_suspend`` one (without the
+intervening ``->runtime_resume`` and so on) and the final state of the device
+must reflect the "active" status for runtime PM in that case.
+
 During system-wide resume from a sleep state it's easiest to put devices into
 the full-power state, as explained in :file:`Documentation/power/runtime_pm.txt`.
 Refer to that document for more information regarding this particular issue as