Devfreq framework supports suspend of its devices.
Call the the devfreq interface and allow devfreq devices
preserve/restore their states during suspend/resume.
Suggested-by: NTobias Jakobi <tjakobi@math.uni-bielefeld.de>
Reviewed-by: NChanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: NLukasz Luba <l.luba@partner.samsung.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

If __device_suspend() runs asynchronously (in which case the device
passed to it is in dpm_suspended_list at that point) and it returns
early on an error or pending wakeup, and the power.direct_complete
flag has been set for the device already, the subsequent
device_resume() will be confused by that and it will call
pm_runtime_enable() incorrectly, as runtime PM has not been
disabled for the device by __device_suspend().

To avoid that, clear power.direct_complete if __device_suspend()
is not going to disable runtime PM for the device before returning.

Fixes: aae4518b (PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily)
Reported-by: NAl Cooper <alcooperx@gmail.com>
Tested-by: NAl Cooper <alcooperx@gmail.com>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Cc: 3.16+ <stable@vger.kernel.org> # 3.16+
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit 08810a41 (PM / core: Add NEVER_SKIP and SMART_PREPARE
driver flags) inadvertently prevented the power.direct_complete flag
from being set for devices without PM callbacks and with disabled
runtime PM which also prevents power.direct_complete from being set
for their parents.  That led to problems including a resume crash on
HP ZBook 14u.

Restore the previous behavior by causing power.direct_complete to be
set for those devices again, but do that in a more direct way to
avoid overlooking that case in the future.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199693
Fixes: 08810a41 (PM / core: Add NEVER_SKIP and SMART_PREPARE driver flags)
Reported-by: NThomas Martitz <kugel@rockbox.org>
Tested-by: NThomas Martitz <kugel@rockbox.org>
Cc: 4.15+ <stable@vger.kernel.org> # 4.15+
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Reviewed-by: NJohan Hovold <johan@kernel.org>

When we print diagnostic messages about suspend/resume, we have a device
pointer, so use dev_printk() to match other device-related things.  Add the
function name, similar to initcall_debug output.  E.g.,

  - calling  0000:01:00.0+ @ 998, parent: 0000:00:1c.0
  + pci 0000:01:00.0: calling <something> @ 998, parent: 0000:00:1c.0

I wondered if this would break scripts/bootgraph.pl, but I don't think it
will because bootgraph.pl doesn't add any timing information to $start{}
after it sees "Write protecting the" or "Freeing unused kernel memory".
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

initcall_debug_report() always called ktime_get(), even if we didn't
need the result.

Change it so we only call it when we're going to use the result, and
change initcall_debug_start() to follow the same style.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit e8bca479 (PM / sleep: trace events for device PM callbacks)
removed the only uses of "state" and "info" from initcall_debug_report().

Remove the now-unused arguments completely.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Currently the wakeup_path status flag becomes propagated from a child
device to its parent device at __device_suspend(). This allows a driver
dealing with a parent device to act on the flag from its ->suspend()
callback.

However, in situations when the wakeup_path status flag needs to be set
from a ->suspend_late() callback, its value doesn't get propagated to the
parent by the PM core. Let's address this limitation, by also propagating
the flag at __device_suspend_late().
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

To make the code more consistent, let's clear the parent's direct_complete
flag along with clearing it for suppliers, instead of as currently, when
propagating the wakeup_path flag to parents.

While changing this, let's take the opportunity to rename the affected
internal functions, to make them self-explanatory. Like this:

dpm_clear_suppliers_direct_complete -> dpm_clear_superiors_direct_complete
dpm_propagate_to_parent -> dpm_propagate_wakeup_to_parent
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The PM core in the device_prepare() phase, resets the wakeup_path status
flag to the value of device_may_wakeup(). This means if a ->prepare() or a
->suspend() callback for the device would update the device's wakeup
setting, this doesn't become reflected in the wakeup_path status flag.

In general this isn't a problem, because wakeup settings are not supposed
to be changed (via for example calling device_set_wakeup_enable()) during
any system wide suspend/resume phase.  Nevertheless there are some users,
which can be considered as legacy, that don't conform to this behaviour.

These legacy cases should be corrected, however until that is done, let's
address the issue from the PM core, by moving the assignment of the
wakeup_path status flag to the __device_suspend() phase and after the
->suspend() callback has been invoked.
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Make the PM core handle DPM_FLAG_LEAVE_SUSPENDED directly for
devices whose "noirq", "late" and "early" driver callbacks are
invoked directly by it.

Namely, make it skip all of the system-wide resume callbacks for
such devices with DPM_FLAG_LEAVE_SUSPENDED set if they are in
runtime suspend during the "noirq" phase of system-wide suspend
(or analogous) transitions or the system transition under way is
a proper suspend (rather than anything related to hibernation) and
the device's wakeup settings are compatible with runtime PM (that
is, the device cannot generate wakeup signals at all or it is
allowed to wake up the system from sleep).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Make the PM core avoid invoking the "late" and "noirq" system-wide
suspend (or analogous) callbacks provided by device drivers directly
for devices with DPM_FLAG_SMART_SUSPEND set that are in runtime
suspend during the "late" and "noirq" phases of system-wide suspend
(or analogous) transitions.  That is only done for devices without
any middle-layer "late" and "noirq" suspend callbacks (to avoid
confusing the middle layer if there is one).

The underlying observation is that runtime PM is disabled for devices
during the "late" and "noirq" system-wide suspend phases, so if they
remain in runtime suspend from the "late" phase forward, it doesn't
make sense to invoke the "late" and "noirq" callbacks provided by
the drivers for them (arguably, the device is already suspended and
in the right state).  Thus, if the remaining driver suspend callbacks
are to be invoked directly by the core, they can be skipped.

This change really makes it possible for, say, platform device
drivers to re-use runtime PM suspend and resume callbacks by
pointing ->suspend_late and ->resume_early, respectively (and
possibly the analogous hibernation-related callback pointers too),
to them without adding any extra "is the device already suspended?"
type of checks to the callback routines, as long as they will be
invoked directly by the core.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Add helper routines to find and return a suitable subsystem callback
during the "noirq" phases of system suspend/resume (or analogous)
transitions as well as during the "late" phase of system suspend and
the "early" phase of system resume (or analogous) transitions.

The helpers will be called from additional sites going forward.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>

Make the PM core call dev_pm_skip_next_resume_phases() to skip the
"early resume" and "resume" phases of system-wide transitions to the
working state for a given device instead of clearing the relevant
status bits for it directly.

No intentional changes in functionality.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>

The file was converted from print_fn_descriptor_symbol()
to %pF some time ago (c80cfb04 "vsprintf: use new
vsprintf symbolic function pointer format"). kallsyms does
not seem to be needed anymore.
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Middle-layer code doing suspend-time optimizations for devices with
the DPM_FLAG_SMART_SUSPEND flag set (currently, the PCI bus type and
the ACPI PM domain) needs to make the core skip ->thaw_early and
->thaw callbacks for those devices in some cases and it sets the
power.direct_complete flag for them for this purpose.

However, it turns out that setting power.direct_complete outside of
the PM core is a bad idea as it triggers an excess invocation of
pm_runtime_enable() in device_resume().

For this reason, provide a helper to clear power.is_late_suspended
and power.is_suspended to be invoked by the middle-layer code in
question instead of setting power.direct_complete and make that code
call the new helper.

Fixes: c4b65157 (PCI / PM: Take SMART_SUSPEND driver flag into account)
Fixes: 05087360 (ACPI / PM: Take SMART_SUSPEND driver flag into account)
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>

Let's make the code a bit more readable by moving some of the code, which
deals with adjustments for parent devices in __device_suspend(), into its
own function.
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Define and document a new driver flag, DPM_FLAG_LEAVE_SUSPENDED, to
instruct the PM core and middle-layer (bus type, PM domain, etc.)
code that it is desirable to leave the device in runtime suspend
after system-wide transitions to the working state (for example,
the device may be slow to resume and it may be better to avoid
resuming it right away).

Generally, the middle-layer code involved in the handling of the
device is expected to indicate to the PM core whether or not the
device may be left in suspend with the help of the device's
power.may_skip_resume status bit.  That has to happen in the "noirq"
phase of the preceding system 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 may be left suspended, but
the other resume callbacks (except for ->complete) will be skipped
automatically by the core if the device really can be left in
suspend.

The additional power.must_resume status bit introduced for the
implementation of this mechanisn is used internally by the PM core
to track the requirement to resume the device (which may depend on
its children etc).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>

Make the PCI bus type take DPM_FLAG_SMART_SUSPEND into account in its
system-wide PM callbacks and make sure that all code that should not
run in parallel with pci_pm_runtime_resume() is executed in the "late"
phases of system suspend, freeze and poweroff transitions.

[Note that the pm_runtime_suspended() check in pci_dev_keep_suspended()
is an optimization, because if is not passed, all of the subsequent
checks may be skipped and some of them are much more overhead in
general.]

Also use the observation that if the device is in runtime suspend
at the beginning of the "late" phase of a system-wide suspend-like
transition, its state cannot change going forward (runtime PM is
disabled for it at that time) until the transition is over and the
subsequent system-wide PM callbacks should be skipped for it (as
they generally assume the device to not be suspended), so add checks
for that in pci_pm_suspend_late/noirq(), pci_pm_freeze_late/noirq()
and pci_pm_poweroff_late/noirq().

Moreover, if pci_pm_resume_noirq() or pci_pm_restore_noirq() is
called during the subsequent system-wide resume transition and if
the device was left in runtime suspend previously, its runtime PM
status needs to be changed to "active" as it is going to be put
into the full-power state, so add checks for that too to these
functions.

In turn, if pci_pm_thaw_noirq() runs after the device has been
left in runtime suspend, the subsequent "thaw" callbacks need
to be skipped for it (as they may not work correctly with a
suspended device), so set the power.direct_complete flag for the
device then to make the PM core skip those callbacks.

In addition to the above add a core helper for checking if
DPM_FLAG_SMART_SUSPEND is set and the device runtime PM status is
"suspended" at the same time, which is done quite often in the new
code (and will be done elsewhere going forward too).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>

Define and document a SMART_SUSPEND flag to instruct bus types and PM
domains that the system suspend callbacks provided by the driver can
cope with runtime-suspended devices, so from the driver's perspective
it should be safe to leave devices in runtime suspend during system
suspend.

Setting that flag may also cause middle-layer code (bus types,
PM domains etc.) to skip invocations of the ->suspend_late and
->suspend_noirq callbacks provided by the driver if the device
is in runtime suspend at the beginning of the "late" phase of
the system-wide suspend transition, in which case the driver's
system-wide resume callbacks may be invoked back-to-back with
its ->runtime_suspend callback, so the driver has to be able to
cope with that too.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>

The motivation for this change is to provide a way to work around
a problem with the direct-complete mechanism used for avoiding
system suspend/resume handling for devices in runtime suspend.

The problem is that some middle layer code (the PCI bus type and
the ACPI PM domain in particular) returns positive values from its
system suspend ->prepare callbacks regardless of whether the driver's
->prepare returns a positive value or 0, which effectively prevents
drivers from being able to control the direct-complete feature.
Some drivers need that control, however, and the PCI bus type has
grown its own flag to deal with this issue, but since it is not
limited to PCI, it is better to address it by adding driver flags at
the core level.

To that end, add a driver_flags field to struct dev_pm_info for flags
that can be set by device drivers at the probe time to inform the PM
core and/or bus types, PM domains and so on on the capabilities and/or
preferences of device drivers.  Also add two static inline helpers
for setting that field and testing it against a given set of flags
and make the driver core clear it automatically on driver remove
and probe failures.

Define and document two PM driver flags related to the direct-
complete feature: NEVER_SKIP and SMART_PREPARE that can be used,
respectively, to indicate to the PM core that the direct-complete
mechanism should never be used for the device and to inform the
middle layer code (bus types, PM domains etc) that it can only
request the PM core to use the direct-complete mechanism for
the device (by returning a positive value from its ->prepare
callback) if it also has been requested by the driver.

While at it, make the core check pm_runtime_suspended() when
setting power.direct_complete so that it doesn't need to be
checked by ->prepare callbacks.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>

Fix the kerneldoc comments of __device_suspend_noirq(),
__device_suspend_late() and __device_suspend() where the function
names in kerneldoc don't match the actual names of the functions.

Also fix the device_resume_noirq() kerneldoc comment which mentions
"early resume" instead of "noirq resume" incorrectly.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>

Remove uses of init_timer_on_stack() with open-coded function and data
assignments that could be expressed using timer_setup_on_stack(). Several
were removed from the stack entirely since there was a one-to-one mapping
of parent structure to timer, those are switched to using timer_setup()
instead. All related callbacks were adjusted to use from_timer().
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: Petr Mladek <pmladek@suse.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: linux1394-devel@lists.sourceforge.net
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: linux-s390@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: linux-scsi@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ursula Braun <ubraun@linux.vnet.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Harish Patil <harish.patil@cavium.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Michael Reed <mdr@sgi.com>
Cc: Manish Chopra <manish.chopra@cavium.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-pm@vger.kernel.org
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Gross <mark.gross@intel.com>
Cc: linux-watchdog@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: netdev@vger.kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lkml.kernel.org/r/1507159627-127660-4-git-send-email-keescook@chromium.org

There are no classes using the legacy suspend/resume operations in
the tree any more, so drop these operations and update the code
referring to them accordingly.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The device_pm_check_callbacks() function doesn't check legacy
->suspend and ->resume callback pointers under the device's
bus type, class and driver, so in some cases it may set the
no_pm_callbacks flag for the device incorrectly and then the
callbacks may be skipped during system suspend/resume, which
shouldn't happen.

Fixes: aa8e54b5 (PM / sleep: Go direct_complete if driver has no callbacks)
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: 4.5+ <stable@vger.kernel.org> # 4.5+

Restore the pm_wakeup_pending() check in __device_suspend_noirq()
removed by commit eed4d47e (ACPI / sleep: Ignore spurious SCI
wakeups from suspend-to-idle) as that allows the function to return
earlier if there's a wakeup event pending already (so that it may
spend less time on carrying out operations that will be reversed
shortly anyway) and rework the main suspend-to-idle loop to take
that optimization into account.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Make the core device suspend/resume code also call dpm_show_time()
on failures and add an error argument to this function so that the
message printed by it can reflect the success or failure condition.

This makes the debug messages in question look less confusing in
the failing cases.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Put the device interrupts disabling and enabling as well as
cpuidle_pause() and cpuidle_resume() called during the "noirq"
stages of system suspend into separate functions to allow the
core suspend-to-idle code to be optimized (later).

The only functional difference this makes is that debug facilities
and diagnostic tools will not include the above operations into the
"noirq" device suspend/resume duration measurements.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Debug messages from the system suspend/hibernation infrastructure can
fill up the entire kernel log buffer in some cases and anyway they
are only useful for debugging.  They depend on CONFIG_PM_DEBUG, but
that is set as a rule as some generally useful diagnostic facilities
depend on it too.

For this reason, avoid printing those messages by default, but make
it possible to turn them on as needed with the help of a new sysfs
attribute under /sys/power/.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The 'info' string appearing in many places points to a .rodata string so
it should be passes as pointer to const.
Signed-off-by: NKrzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The pm_verb() returns a pointer to string from .rodata so it should be
marked as const.
Signed-off-by: NKrzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The ACPI SCI (System Control Interrupt) is set up as a wakeup IRQ
during suspend-to-idle transitions and, consequently, any events
signaled through it wake up the system from that state.  However,
on some systems some of the events signaled via the ACPI SCI while
suspended to idle should not cause the system to wake up.  In fact,
quite often they should just be discarded.

Arguably, systems should not resume entirely on such events, but in
order to decide which events really should cause the system to resume
and which are spurious, it is necessary to resume up to the point
when ACPI SCIs are actually handled and processed, which is after
executing dpm_resume_noirq() in the system resume path.

For this reasons, add a loop around freeze_enter() in which the
platforms can process events signaled via multiplexed IRQ lines
like the ACPI SCI and add suspend-to-idle hooks that can be
used for this purpose to struct platform_freeze_ops.

In the ACPI case, the ->wake hook is used for checking if the SCI
has triggered while suspended and deferring the interrupt-induced
system wakeup until the events signaled through it are actually
processed sufficiently to decide whether or not the system should
resume.  In turn, the ->sync hook allows all of the relevant event
queues to be flushed so as to prevent events from being missed due
to race conditions.

In addition to that, some ACPI code processing wakeup events needs
to be modified to use the "hard" version of wakeup triggers, so that
it will cause a system resume to happen on device-induced wakeup
events even if the "soft" mechanism to prevent the system from
suspending is not enabled.  However, to preserve the existing
behavior with respect to suspend-to-RAM, this only is done in
the suspend-to-idle case and only if an SCI has occurred while
suspended.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Avoid printing the device suspend/resume timing information if
CONFIG_PM_DEBUG is not set to reduce the log noise level.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Revert commit eed4d47e (ACPI / sleep: Ignore spurious SCI wakeups
from suspend-to-idle) as it turned out to be premature and triggered
a number of different issues on various systems.

That includes, but is not limited to, premature suspend-to-RAM aborts
on Dell XPS 13 (9343) reported by Dominik.

The issue the commit in question attempted to address is real and
will need to be taken care of going forward, but evidently more work
is needed for this purpose.
Reported-by: NDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The ACPI SCI (System Control Interrupt) is set up as a wakeup IRQ
during suspend-to-idle transitions and, consequently, any events
signaled through it wake up the system from that state.  However,
on some systems some of the events signaled via the ACPI SCI while
suspended to idle should not cause the system to wake up.  In fact,
quite often they should just be discarded.

Arguably, systems should not resume entirely on such events, but in
order to decide which events really should cause the system to resume
and which are spurious, it is necessary to resume up to the point
when ACPI SCIs are actually handled and processed, which is after
executing dpm_resume_noirq() in the system resume path.

For this reasons, add a loop around freeze_enter() in which the
platforms can process events signaled via multiplexed IRQ lines
like the ACPI SCI and add suspend-to-idle hooks that can be
used for this purpose to struct platform_freeze_ops.

In the ACPI case, the ->wake hook is used for checking if the SCI
has triggered while suspended and deferring the interrupt-induced
system wakeup until the events signaled through it are actually
processed sufficiently to decide whether or not the system should
resume.  In turn, the ->sync hook allows all of the relevant event
queues to be flushed so as to prevent events from being missed due
to race conditions.

In addition to that, some ACPI code processing wakeup events needs
to be modified to use the "hard" version of wakeup triggers, so that
it will cause a system resume to happen on device-induced wakeup
events even if the "soft" mechanism to prevent the system from
suspending is not enabled (that also helps to catch device-induced
wakeup events occurring during suspend transitions in progress).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

ktime_set(S,N) was required for the timespec storage type and is still
useful for situations where a Seconds and Nanoseconds part of a time value
needs to be converted. For anything where the Seconds argument is 0, this
is pointless and can be replaced with a simple assignment.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>

If async_suspend is enabled for parent and child devices, then
PM framework has to ensure that parent's async suspend gets called
only after child's async suspend is done. In case if child's async
suspend fails with error, then parent's async suspend must not be
invoked. The current code uses async_error to ensure this but there
is a problem with it in __device_suspend(). This function notifies
the completion of child's async suspend before updating its error
via async_error variable. As a result, parent's async suspend gets
invoked even though it's child suspend has failed. Fix this bug by
updating the async_error before notifying the child's completion.
Signed-off-by: NSahitya Tummala <stummala@codeaurora.org>
[ rjw: Rearranged wthitespace ]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Consider two devices, A and B, where B is a child of A, and B utilizes
asynchronous suspend (it does not matter whether A is sync or async). If
B fails to suspend_noirq() or suspend_late(), or is interrupted by a
wakeup (pm_wakeup_pending()), then it aborts and sets the async_error
variable. However, device A does not (immediately) check the async_error
variable; it may continue to run its own suspend_noirq()/suspend_late()
callback. This is bad.

We can resolve this problem by doing our error and wakeup checking
(particularly, for the async_error flag) after waiting for children to
suspend, instead of before. This also helps align the logic for the noirq and
late suspend cases with the logic in __device_suspend().

It's easy to observe this erroneous behavior by, for example, forcing a
device to sleep a bit in its suspend_noirq() (to ensure the parent is
waiting for the child to complete), then return an error, and watch the
parent suspend_noirq() still get called. (Or similarly, fake a wakeup
event at the right (or is it wrong?) time.)

Fixes: de377b39 (PM / sleep: Asynchronous threads for suspend_late)
Fixes: 28b6fd6e (PM / sleep: Asynchronous threads for suspend_noirq)
Reported-by: NJeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: NBrian Norris <briannorris@chromium.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Make the device suspend/resume part of the core system
suspend/resume code use device links to ensure that supplier
and consumer devices will be suspended and resumed in the right
order in case of async suspend/resume.

The idea, roughly, is to use dpm_wait() to wait for all consumers
before a supplier device suspend and to wait for all suppliers
before a consumer device resume.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently, there is a problem with taking functional dependencies
between devices into account.

What I mean by a "functional dependency" is when the driver of device
B needs device A to be functional and (generally) its driver to be
present in order to work properly.  This has certain consequences
for power management (suspend/resume and runtime PM ordering) and
shutdown ordering of these devices.  In general, it also implies that
the driver of A needs to be working for B to be probed successfully
and it cannot be unbound from the device before the B's driver.

Support for representing those functional dependencies between
devices is added here to allow the driver core to track them and act
on them in certain cases where applicable.

The argument for doing that in the driver core is that there are
quite a few distinct use cases involving device dependencies, they
are relatively hard to get right in a driver (if one wants to
address all of them properly) and it only gets worse if multiplied
by the number of drivers potentially needing to do it.  Morever, at
least one case (asynchronous system suspend/resume) cannot be handled
in a single driver at all, because it requires the driver of A to
wait for B to suspend (during system suspend) and the driver of B to
wait for A to resume (during system resume).

For this reason, represent dependencies between devices as "links",
with the help of struct device_link objects each containing pointers
to the "linked" devices, a list node for each of them, status
information, flags, and an RCU head for synchronization.

Also add two new list heads, representing the lists of links to the
devices that depend on the given one (consumers) and to the devices
depended on by it (suppliers), and a "driver presence status" field
(needed for figuring out initial states of device links) to struct
device.

The entire data structure consisting of all of the lists of link
objects for all devices is protected by a mutex (for link object
addition/removal and for list walks during device driver probing
and removal) and by SRCU (for list walking in other case that will
be introduced by subsequent change sets).  If CONFIG_SRCU is not
selected, however, an rwsem is used for protecting the entire data
structure.

In addition, each link object has an internal status field whose
value reflects whether or not drivers are bound to the devices
pointed to by the link or probing/removal of their drivers is in
progress etc.  That field is only modified under the device links
mutex, but it may be read outside of it in some cases (introduced by
subsequent change sets), so modifications of it are annotated with
WRITE_ONCE().

New links are added by calling device_link_add() which takes three
arguments: pointers to the devices in question and flags.  In
particular, if DL_FLAG_STATELESS is set in the flags, the link status
is not to be taken into account for this link and the driver core
will not manage it.  In turn, if DL_FLAG_AUTOREMOVE is set in the
flags, the driver core will remove the link automatically when the
consumer device driver unbinds from it.

One of the actions carried out by device_link_add() is to reorder
the lists used for device shutdown and system suspend/resume to
put the consumer device along with all of its children and all of
its consumers (and so on, recursively) to the ends of those lists
in order to ensure the right ordering between all of the supplier
and consumer devices.

For this reason, it is not possible to create a link between two
devices if the would-be supplier device already depends on the
would-be consumer device as either a direct descendant of it or a
consumer of one of its direct descendants or one of its consumers
and so on.

There are two types of link objects, persistent and non-persistent.
The persistent ones stay around until one of the target devices is
deleted, while the non-persistent ones are removed automatically when
the consumer driver unbinds from its device (ie. they are assumed to
be valid only as long as the consumer device has a driver bound to
it).  Persistent links are created by default and non-persistent
links are created when the DL_FLAG_AUTOREMOVE flag is passed
to device_link_add().

Both persistent and non-persistent device links can be deleted
with an explicit call to device_link_del().

Links created without the DL_FLAG_STATELESS flag set are managed
by the driver core using a simple state machine.  There are 5 states
each link can be in: DORMANT (unused), AVAILABLE (the supplier driver
is present and functional), CONSUMER_PROBE (the consumer driver is
probing), ACTIVE (both supplier and consumer drivers are present and
functional), and SUPPLIER_UNBIND (the supplier driver is unbinding).
The driver core updates the link state automatically depending on
what happens to the linked devices and for each link state specific
actions are taken in addition to that.

For example, if the supplier driver unbinds from its device, the
driver core will also unbind the drivers of all of its consumers
automatically under the assumption that they cannot function
properly without the supplier.  Analogously, the driver core will
only allow the consumer driver to bind to its device if the
supplier driver is present and functional (ie. the link is in
the AVAILABLE state).  If that's not the case, it will rely on
the existing deferred probing mechanism to wait for the supplier
driver to become available.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>