Merge branch 'pm-core'

* pm-core: (29 commits)
  dmaengine: rcar-dmac: Make DMAC reinit during system resume explicit
  PM / runtime: Allow no callbacks in pm_runtime_force_suspend|resume()
  PM / runtime: Check ignore_children in pm_runtime_need_not_resume()
  PM / runtime: Rework pm_runtime_force_suspend/resume()
  PM / wakeup: Print warn if device gets enabled as wakeup source during sleep
  PM / core: Propagate wakeup_path status flag in __device_suspend_late()
  PM / core: Re-structure code for clearing the direct_complete flag
  PM: i2c-designware-platdrv: Optimize power management
  PM: i2c-designware-platdrv: Use DPM_FLAG_SMART_PREPARE
  PM / mfd: intel-lpss: Use DPM_FLAG_SMART_SUSPEND
  PCI / PM: Use SMART_SUSPEND and LEAVE_SUSPENDED flags for PCIe ports
  PM / wakeup: Add device_set_wakeup_path() helper to control wakeup path
  PM / core: Assign the wakeup_path status flag in __device_prepare()
  PM / wakeup: Do not fail dev_pm_attach_wake_irq() unnecessarily
  PM / core: Direct DPM_FLAG_LEAVE_SUSPENDED handling
  PM / core: Direct DPM_FLAG_SMART_SUSPEND optimization
  PM / core: Add helpers for subsystem callback selection
  PM / wakeup: Drop redundant check from device_init_wakeup()
  PM / wakeup: Drop redundant check from device_set_wakeup_enable()
  PM / wakeup: only recommend "call"ing device_init_wakeup() once
  ...

2 files changed, 55 insertions, 10 deletions

diff --git a/Documentation/driver-api/pm/devices.rst b/Documentation/driver-api/pm/devices.rst
index 53c1b0b06da5..1128705a5731 100644
--- a/Documentation/driver-api/pm/devices.rst
+++ b/Documentation/driver-api/pm/devices.rst
@@ -777,17 +777,51 @@ The driver can indicate that by setting ``DPM_FLAG_SMART_SUSPEND`` 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.
+after that point until the system-wide transition is over (the PM core itself
+does that for devices whose "noirq", "late" and "early" system-wide PM callbacks
+are executed directly by it).  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" runtime PM
+status 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
+[Refer to that document for more information regarding this particular issue as
 well as for information on the device runtime power management framework in
-general.
+general.]
+
+However, it often is desirable to leave devices in suspend after system
+transitions to the working state, especially if those devices had been in
+runtime suspend before the preceding system-wide suspend (or analogous)
+transition.  Device drivers can use the ``DPM_FLAG_LEAVE_SUSPENDED`` flag to
+indicate to the PM core (and middle-layer code) that they prefer the specific
+devices handled by them to be left suspended and they have no problems with
+skipping their system-wide resume callbacks for this reason.  Whether or not the
+devices will actually be left in suspend may depend on their state before the
+given system suspend-resume cycle and on the type of the system transition under
+way.  In particular, devices are not left suspended if that transition is a
+restore from hibernation, as device states are not guaranteed to be reflected
+by the information stored in the hibernation image in that case.
+
+The middle-layer code involved in the handling of the device is expected to
+indicate to the PM core if the device may be left in suspend by setting its
+:c:member:`power.may_skip_resume` status bit which is checked by the PM core
+during the "noirq" phase of the preceding system-wide suspend (or analogous)
+transition.  The middle layer is then responsible for handling the device as
+appropriate in its "noirq" resume callback, which is executed regardless of
+whether or not the device is left suspended, but the other resume callbacks
+(except for ``->complete``) will be skipped automatically by the PM core if the
+device really can be left in suspend.
+
+For devices whose "noirq", "late" and "early" driver callbacks are invoked
+directly by the PM core, all of the system-wide resume callbacks are skipped if
+``DPM_FLAG_LEAVE_SUSPENDED`` is set and the device is in runtime suspend during
+the ``suspend_noirq`` (or analogous) phase or the transition under way is a
+proper system suspend (rather than anything related to hibernation) and the
+device's wakeup settings are suitable for runtime PM (that is, it cannot
+generate wakeup signals at all or it is allowed to wake up the system from
+sleep).
diff --git a/Documentation/power/pci.txt b/Documentation/power/pci.txt
index 704cd36079b8..8eaf9ee24d43 100644
--- a/Documentation/power/pci.txt
+++ b/Documentation/power/pci.txt
@@ -994,6 +994,17 @@ into D0 going forward), but if it is in runtime suspend in pci_pm_thaw_noirq(),
 the function will set the power.direct_complete flag for it (to make the PM core
 skip the subsequent "thaw" callbacks for it) and return.
 
+Setting the DPM_FLAG_LEAVE_SUSPENDED flag means that the driver prefers the
+device to be left in suspend after system-wide transitions to the working state.
+This flag is checked by the PM core, but the PCI bus type informs the PM core
+which devices may be left in suspend from its perspective (that happens during
+the "noirq" phase of system-wide suspend and analogous transitions) and next it
+uses the dev_pm_may_skip_resume() helper to decide whether or not to return from
+pci_pm_resume_noirq() early, as the PM core will skip the remaining resume
+callbacks for the device during the transition under way and will set its
+runtime PM status to "suspended" if dev_pm_may_skip_resume() returns "true" for
+it.
+
 3.2. Device Runtime Power Management
 ------------------------------------
 In addition to providing device power management callbacks PCI device drivers