* intel_pstate:
  cpufreq: intel_pstate: Avoid division by 0 in min_perf_pct_min()

* pm-sleep:
  Revert "ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle"

Revert commit eed4d47efe95 (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: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

* acpi-button:
  Revert "ACPI / button: Change default behavior to lid_init_state=open"

* acpica:
  ACPICA: Tables: Fix regression introduced by a too early mechanism enabling

* acpi-sysfs:
  ACPI / sysfs: fix acpi_get_table() leak / acpi-sysfs denial of service

Revert commit 77e9a4aa9de1 (ACPI / button: Change default behavior to
lid_init_state=open) which changed the kernel's behavior on laptops
that boot with closed lids and expect the lid switch state to be
reported accurately by the kernel.

If you boot or resume your laptop with the lid closed on a docking
station while using an external monitor connected to it, both internal
and external displays will light on, while only the external should.

There is a design choice in gdm to only provide the greeter on the
internal display when lit on, so users only see a gray area on the
external monitor. Also, the cursor will not show up as it's by
default on the internal display too.

To "fix" that, users have to open the laptop once and close it once
again to sync the state of the switch with the hardware state.

Even if the "method" operation mode implementation can be buggy on
some platforms, the "open" choice is worse.  It breaks docking
stations basically and there is no way to have a user-space hwdb to
fix that.

On the contrary, it's rather easy in user-space to have a hwdb
with the problematic platforms. Then,  libinput (1.7.0+) can fix
the state of the lid switch for us: you need to set the udev
property LIBINPUT_ATTR_LID_SWITCH_RELIABILITY to 'write_open'.

When libinput detects internal keyboard events, it will overwrite the
state of the switch to open, making it reliable again.  Given that
logind only checks the lid switch value after a timeout, we can
assume the user will use the internal keyboard before this timeout
expires.

For example, such a hwdb entry is:

libinput:name:*Lid Switch*:dmi:*svnMicrosoftCorporation:pnSurface3:*
 LIBINPUT_ATTR_LID_SWITCH_RELIABILITY=write_open

Link: https://bugzilla.gnome.org/show_bug.cgi?id=782380
Cc: 4.11+ <stable@vger.kernel.org> # 4.11+
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

* acpi-button:
  Revert "ACPI / button: Remove lid_init_state=method mode"

* acpi-tools:
  tools/power/acpi: Add .gitignore file

This reverts commit ecb10b694b72ca5ea51b3c90a71ff2a11963425a.

The only expected ACPI control method lid device's usage model is

 1. Listen to the lid notification,
 2. Evaluate _LID after being notified by BIOS,
 3. Suspend the system (if users configure to do so) after seeing "close".

It's not ensured that BIOS will notify OS after boot/resume, and
it's not ensured that BIOS will always generate "open" event upon
opening the lid.

But there are 2 wrong usage models:

 1. When the lid device is responsible for suspend/resume the system,
    userspace requires to see "open" event to be paired with "close" after
    the system is resumed, or it will suspend the system again.

 2. When an external monitor connects to the laptop attached docks,
    userspace requires to see "close" event after the system is resumed so
    that it can determine whether the internal display should remain dark
    and the external display should be lit on.

After we made default kernel behavior to be suitable for usage model 1,
users of usage model 2 start to report regressions for such behavior
change.

Reversion of button.lid_init_state=method doesn't actually reverts to old
default behavior as doing so can enter a regression loop, but facilitates
users to work the reported regressions around with
button.lid_init_state=method.

Fixes: ecb10b694b72 (ACPI / button: Remove lid_init_state=method mode)
Cc: 4.11+ <stable@vger.kernel.org> # 4.11+
Link: https://bugzilla.kernel.org/show_bug.cgi?id=195455
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1430259
Tested-by: Steffen Weber <steffen.weber@gmail.com>
Tested-by: Julian Wiedmann <julian.wiedmann@jwi.name>
Reported-by: Joachim Frieben <jfrieben@hotmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael 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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The mode is buggy, and lid_init__state=open is more useful than this
mode, so this patch makes it deprecated.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

More and more platforms need the button.lid_init_state=open quirk. This
patch sets it the default behavior.

If a platform doesn't send lid open event or lid open event is lost due to
the underlying system problems, then we can compare various combinations:
1. systemd/acpid is used to suspend system or not, systemd has a special
   logic forcing open event after resuming;
2. _LID returns a cached value or not.

The result is as follows:

 1. lid_init_state=method
   1. cached
      1. resumed by lid:
         (x) event=close
         (x) systemd=suspends again
         (x) acpid=suspends again
         (x) state=close
      2. resumed by other:
         (o) event=close
         (x) systemd=suspends again
         (x) acpid=suspends again
         (o) state=close
   2. non-cached
      1. resumed by lid:
         (o) event=open
         (o) systemd=resumes
         (o) acpid=resumes
         (o) state=open
      2. resumed by other:
         (o) event=close
         (x) systemd=suspends again
         (x) acpid=suspends again
         (o) state=close
 2. lid_init_state=open
   1. cached
      1. resumed by lid:
         (o) event=open
         (o) systemd=resumes
         (o) acpid=resumes
         (x) state=close
      2. resumed by other:
         (x) event=open
         (o) systemd=resumes
         (o) acpid=resumes
         (o) state=close
   2. non-cached
      1. resumed by lid:
         (o) event=open
         (o) systemd=resumes
         (o) acpid=resumes
         (o) state=open
      2. resumed by other:
         (x) event=open
         (o) systemd=resumes
         (o) acpid=resumes
         (o) state=close
 3. lid_init_state=ignore
   1. cached
      1. resumed by lid:
         (o) event=none
         (x) systemd=suspends again
         (o) acpid=resumes
         (x) state=close
      2. resumed by other:
         (o) event=none
         (x) systemd=suspends again
         (o) acpid=resumes
         (o) state=close
   2. non-cached
      1. resumed by lid:
         (o) event=none
         (x) systemd=suspends again
         (o) acpid=resumes
         (o) state=open
      2. resumed by other:
         (o) event=none
         (x) systemd=suspends again
         (o) acpid=resumes
         (o) state=close

As a conclusion:
 1. With systemd changed, lid_init_state=ignore has only one problem and the
    problem comes from an underlying issue, not userspace and kernel lid
    handling.
 2. Without systemd changed, lid_init_state=open can be the default
    behavior as the pass ratio is not much worse than lid_init_state=ignore.
 3. lid_init_state=method is buggy, we can have a separate patch to make it
    deprectated.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=187271
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

On most platforms, _LID returning value, lid open/close events are all
reliable, but there are exceptions. Some AML tables report wrong initial
lid state [1], and some of them never report lid open state [2].
The usage model on such buggy platforms is:
1. The initial lid state returned from _LID is not reliable;
2. The lid open event is not reliable;
3. The lid close event is always reliable, used by the platform firmware to
   trigger OSPM power saving operations.
This usage model is not compliant to the Linux SW_LID model as the Linux
userspace is very strict to the reliability of the open events.

In order not to trigger issues on such buggy platforms, the ACPI button
driver currently implements a lid_init_state=open quirk to send additional
"open" event after resuming. However, this is still not sufficient because:
1. Some special usage models (e.x., the dark resume scenario) cannot be
   supported by this mode.
2. If a "close" event is not used to trigger "suspend", then the subsequent
   "close" events cannot be seen by the userspace.
So we need to stop sending the additional "open" event and switch the
driver to lid_init_state=ignore mode and make sure the platform triggered
events can be reliably delivered to the userspace. The userspace programs
then can be changed to not to be strict to the "open" events on such buggy
platforms.

Why will the subsequent "close" events be lost? This is because the input
layer automatically filters redundant events for switch events. Thus given
that the buggy AML tables do not guarantee paired "open"/"close" events,
the ACPI button driver currently is not able to guarantee that the platform
triggered reliable events can be always be seen by the userspace via
SW_LID.

This patch adds a mechanism to insert lid events as a compensation for the
platform triggered ones to form a complete event switches in order to make
sure that the platform triggered events can always be reliably delivered
to the userspace. This essentially guarantees that the platform triggered
reliable "close" events will always be relibly delivered to the userspace.

However this mechanism is not suitable for lid_init_state=open/method as
it should not send the complement switch event for the unreliable initial
lid state notification. 2 unreliable events can trigger unexpected
behavior. Thus this patch only implements this mechanism for
lid_init_state=ignore.

Known issues:
1. Possible alternative approach
   This approach is based on the fact that Linux requires a switch event
   type for LID events. Another approach is to use key event type to
   implement ACPI lid events.
   With SW event type, since ACPI button driver inserts wrong lid events,
   there could be a potential issue that an "open" event issued from some
   AML update methods could result in a wrong "close" event to be delivered
   to the userspace. While using KEY event type, there is no such problem.
   However there may not be such a kind of real case, and if there is such
   a case, it is worked around in this patch as the complement switch event
   is only generated for "close" event in order to deliver the reliable
   "close" event to the userspace.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=89211 # [1]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=106151 # [1]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=106941 # [2]
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Suggested-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>