linux.git/drivers/acpi/internal.h, branch v4.13 Linux kernel source tree ACPI: EC: Fix regression related to wrong ECDT initialization order 2017-08-17T18:52:19+00:00 Lv Zheng lv.zheng@intel.com 2017-08-16T07:29:49+00:00 98529b9272e06a7767034fb8a32e43cdecda240a Commit 2a5708409e4e (ACPI / EC: Fix a gap that ECDT EC cannot handle EC events) introduced acpi_ec_ecdt_start(), but that function is invoked before acpi_ec_query_init(), which is too early. This causes the kernel to crash if an EC event occurs after boot, when ec_query_wq is not valid: BUG: unable to handle kernel NULL pointer dereference at 0000000000000102 ... Workqueue: events acpi_ec_event_handler task: ffff9f539790dac0 task.stack: ffffb437c0e10000 RIP: 0010:__queue_work+0x32/0x430 Normally, the DSDT EC should always be valid, so acpi_ec_ecdt_start() is actually a no-op in the majority of cases. However, commit c712bb58d827 (ACPI / EC: Add support to skip boot stage DSDT probe) caused the probing of the DSDT EC as the "boot EC" to be skipped when the ECDT EC is valid and uncovered the bug. Fix this issue by invoking acpi_ec_ecdt_start() after acpi_ec_query_init() in acpi_ec_init(). Link: https://jira01.devtools.intel.com/browse/LCK-4348 Fixes: 2a5708409e4e (ACPI / EC: Fix a gap that ECDT EC cannot handle EC events) Fixes: c712bb58d827 (ACPI / EC: Add support to skip boot stage DSDT probe) Reported-by: Wang Wendy <wendy.wang@intel.com> Tested-by: Feng Chenzhou <chenzhoux.feng@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> [ rjw: Changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Commit 2a5708409e4e (ACPI / EC: Fix a gap that ECDT EC cannot handle
EC events) introduced acpi_ec_ecdt_start(), but that function is
invoked before acpi_ec_query_init(), which is too early.  This causes
the kernel to crash if an EC event occurs after boot, when ec_query_wq
is not valid:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000102
 ...
 Workqueue: events acpi_ec_event_handler
 task: ffff9f539790dac0 task.stack: ffffb437c0e10000
 RIP: 0010:__queue_work+0x32/0x430

Normally, the DSDT EC should always be valid, so acpi_ec_ecdt_start()
is actually a no-op in the majority of cases.  However, commit
c712bb58d827 (ACPI / EC: Add support to skip boot stage DSDT probe)
caused the probing of the DSDT EC as the "boot EC" to be skipped when
the ECDT EC is valid and uncovered the bug.

Fix this issue by invoking acpi_ec_ecdt_start() after acpi_ec_query_init()
in acpi_ec_init().

Link: https://jira01.devtools.intel.com/browse/LCK-4348
Fixes: 2a5708409e4e (ACPI / EC: Fix a gap that ECDT EC cannot handle EC events)
Fixes: c712bb58d827 (ACPI / EC: Add support to skip boot stage DSDT probe)
Reported-by: Wang Wendy <wendy.wang@intel.com>
Tested-by: Feng Chenzhou <chenzhoux.feng@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / PM / EC: Flush all EC work in acpi_freeze_sync() 2017-07-20T14:44:24+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2017-07-20T01:43:12+00:00 880a66275ef4d1e08e5d4dcf4cec768de18c68ef Commit eed4d47efe95 (ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle) introduced acpi_freeze_sync() whose purpose is to flush all of the processing of possible wakeup events signaled via the ACPI SCI. However, it doesn't flush the query workqueue used by the EC driver, so the events generated by the EC may not be processed timely which leads to issues (increased overhead at least, lost events possibly). To fix that introduce acpi_ec_flush_work() that will flush all of the outstanding EC work and call it from acpi_freeze_sync(). Fixes: eed4d47efe95 (ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle) Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Commit eed4d47efe95 (ACPI / sleep: Ignore spurious SCI wakeups from
suspend-to-idle) introduced acpi_freeze_sync() whose purpose is to
flush all of the processing of possible wakeup events signaled via
the ACPI SCI.  However, it doesn't flush the query workqueue used
by the EC driver, so the events generated by the EC may not be
processed timely which leads to issues (increased overhead at least,
lost events possibly).

To fix that introduce acpi_ec_flush_work() that will flush all of
the outstanding EC work and call it from acpi_freeze_sync().

Fixes: eed4d47efe95 (ACPI / sleep: Ignore spurious SCI wakeups from suspend-to-idle)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge tag 'devprop-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2017-07-10T22:23:45+00:00 Linus Torvalds torvalds@linux-foundation.org 2017-07-10T22:23:45+00:00 548aa0e3c516d906dae5edb1fc9a1ad2e490120a Pull device properties framework updates from Rafael Wysocki: "These mostly rearrange the device properties core code and add a few helper functions to it as a foundation for future work. Specifics: - Rearrange the core device properties code by moving the code specific to each supported platform configuration framework (ACPI, DT and build-in) into a separate file (Sakari Ailus). - Add helper functions for accessing device properties in a firmware-agnostic way (Sakari Ailus, Kieran Bingham)" * tag 'devprop-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: device property: Add fwnode_graph_get_port_parent device property: Add FW type agnostic fwnode_graph_get_remote_node device property: Introduce fwnode_device_is_available() device property: Move fwnode graph ops to firmware specific locations device property: Move FW type specific functionality to FW specific files ACPI: Constify argument to acpi_device_is_present() 
Pull device properties framework updates from Rafael Wysocki:
 "These mostly rearrange the device properties core code and add a few
  helper functions to it as a foundation for future work.

  Specifics:

   - Rearrange the core device properties code by moving the code
     specific to each supported platform configuration framework (ACPI,
     DT and build-in) into a separate file (Sakari Ailus).

   - Add helper functions for accessing device properties in a
     firmware-agnostic way (Sakari Ailus, Kieran Bingham)"

* tag 'devprop-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  device property: Add fwnode_graph_get_port_parent
  device property: Add FW type agnostic fwnode_graph_get_remote_node
  device property: Introduce fwnode_device_is_available()
  device property: Move fwnode graph ops to firmware specific locations
  device property: Move FW type specific functionality to FW specific files
  ACPI: Constify argument to acpi_device_is_present()
ACPI / sleep: EC-based wakeup from suspend-to-idle on recent systems 2017-06-23T13:24:32+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2017-06-23T13:24:32+00:00 8110dd281e155e5010ffd657bba4742ebef7a93f Some recent Dell laptops, including the XPS13 model numbers 9360 and 9365, cannot be woken up from suspend-to-idle by pressing the power button which is unexpected and makes that feature less usable on those systems. Moreover, on the 9365 ACPI S3 (suspend-to-RAM) is not expected to be used at all (the OS these systems ship with never exercises the ACPI S3 path in the firmware) and suspend-to-idle is the only viable system suspend mechanism there. The reason why the power button wakeup from suspend-to-idle doesn't work on those systems is because their power button events are signaled by the EC (Embedded Controller), whose GPE (General Purpose Event) line is disabled during suspend-to-idle transitions in Linux. That is done on purpose, because in general the EC tends to be noisy for various reasons (battery and thermal updates and similar, for example) and all events signaled by it would kick the CPUs out of deep idle states while in suspend-to-idle, which effectively might defeat its purpose. Of course, on the Dell systems in question the EC GPE must be enabled during suspend-to-idle transitions for the button press events to be signaled while suspended at all, but fortunately there is a way out of this puzzle. First of all, those systems have the ACPI_FADT_LOW_POWER_S0 flag set in their ACPI tables, which means that the OS is expected to prefer the "low power S0 idle" system state over ACPI S3 on them. That causes the most recent versions of other OSes to simply ignore ACPI S3 on those systems, so it is reasonable to expect that it should not be necessary to block GPEs during suspend-to-idle on them. Second, in addition to that, the systems in question provide a special firmware interface that can be used to indicate to the platform that the OS is transitioning into a system-wide low-power state in which certain types of activity are not desirable or that it is leaving such a state and that (in principle) should allow the platform to adjust its operation mode accordingly. That interface is a special _DSM object under a System Power Management Controller device (PNP0D80). The expected way to use it is to invoke function 0 from it on system initialization, functions 3 and 5 during suspend transitions and functions 4 and 6 during resume transitions (to reverse the actions carried out by the former). In particular, function 5 from the "Low-Power S0" device _DSM is expected to cause the platform to put itself into a low-power operation mode which should include making the EC less verbose (so to speak). Next, on resume, function 6 switches the platform back to the "working-state" operation mode. In accordance with the above, modify the ACPI suspend-to-idle code to look for the "Low-Power S0" _DSM interface on platforms with the ACPI_FADT_LOW_POWER_S0 flag set in the ACPI tables. If it's there, use it during suspend-to-idle transitions as prescribed and avoid changing the GPE configuration in that case. [That should reflect what the most recent versions of other OSes do.] Also modify the ACPI EC driver to make it handle events during suspend-to-idle in the usual way if the "Low-Power S0" _DSM interface is going to be used to make the power button events work while suspended on the Dell machines mentioned above Link: http://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Some recent Dell laptops, including the XPS13 model numbers 9360 and
9365, cannot be woken up from suspend-to-idle by pressing the power
button which is unexpected and makes that feature less usable on
those systems.  Moreover, on the 9365 ACPI S3 (suspend-to-RAM) is
not expected to be used at all (the OS these systems ship with never
exercises the ACPI S3 path in the firmware) and suspend-to-idle is
the only viable system suspend mechanism there.

The reason why the power button wakeup from suspend-to-idle doesn't
work on those systems is because their power button events are
signaled by the EC (Embedded Controller), whose GPE (General Purpose
Event) line is disabled during suspend-to-idle transitions in Linux.
That is done on purpose, because in general the EC tends to be noisy
for various reasons (battery and thermal updates and similar, for
example) and all events signaled by it would kick the CPUs out of
deep idle states while in suspend-to-idle, which effectively might
defeat its purpose.

Of course, on the Dell systems in question the EC GPE must be enabled
during suspend-to-idle transitions for the button press events to
be signaled while suspended at all, but fortunately there is a way
out of this puzzle.

First of all, those systems have the ACPI_FADT_LOW_POWER_S0 flag set
in their ACPI tables, which means that the OS is expected to prefer
the "low power S0 idle" system state over ACPI S3 on them.  That
causes the most recent versions of other OSes to simply ignore ACPI
S3 on those systems, so it is reasonable to expect that it should not
be necessary to block GPEs during suspend-to-idle on them.

Second, in addition to that, the systems in question provide a special
firmware interface that can be used to indicate to the platform that
the OS is transitioning into a system-wide low-power state in which
certain types of activity are not desirable or that it is leaving
such a state and that (in principle) should allow the platform to
adjust its operation mode accordingly.

That interface is a special _DSM object under a System Power
Management Controller device (PNP0D80).  The expected way to use it
is to invoke function 0 from it on system initialization, functions
3 and 5 during suspend transitions and functions 4 and 6 during
resume transitions (to reverse the actions carried out by the
former).  In particular, function 5 from the "Low-Power S0" device
_DSM is expected to cause the platform to put itself into a low-power
operation mode which should include making the EC less verbose (so to
speak).  Next, on resume, function 6 switches the platform back to
the "working-state" operation mode.

In accordance with the above, modify the ACPI suspend-to-idle code
to look for the "Low-Power S0" _DSM interface on platforms with the
ACPI_FADT_LOW_POWER_S0 flag set in the ACPI tables.  If it's there,
use it during suspend-to-idle transitions as prescribed and avoid
changing the GPE configuration in that case.  [That should reflect
what the most recent versions of other OSes do.]

Also modify the ACPI EC driver to make it handle events during
suspend-to-idle in the usual way if the "Low-Power S0" _DSM interface
is going to be used to make the power button events work while
suspended on the Dell machines mentioned above

Link: http://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI: Constify argument to acpi_device_is_present() 2017-06-22T00:55:34+00:00 Sakari Ailus sakari.ailus@linux.intel.com 2017-06-06T09:37:36+00:00 cde1f95f407a593ad6baf1b7b01daa2c6cbd34fd This will be needed in constifying the fwnode API. The side effects the function had have been moved to the callers. Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
This will be needed in constifying the fwnode API.

The side effects the function had have been moved to the callers.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / PM: Ignore spurious SCI wakeups from suspend-to-idle 2017-06-14T22:55:44+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2017-06-12T20:56:34+00:00 33e4f80ee69b5168badf37edbfed796eb48434b9 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: 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.  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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / scan: Drop support for force_remove 2017-04-13T01:51:47+00:00 Michal Hocko mhocko@suse.com 2017-04-03T07:40:23+00:00 ffc10d82ff5df7087a9b737de55a69ac4f89bf56 /sys/firmware/acpi/hotplug/force_remove was presumably added to support auto offlining in the past. This is, however, inherently dangerous for some hotplugable resources like memory. The memory offlining fails when the memory is still in use and cannot be dropped or migrated. If we ignore the failure we are basically allowing for subtle memory corruption or a crash. We have actually noticed the later while hitting BUG() during the memory hotremove (remove_memory): ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL, check_memblock_offlined_cb); if (ret) BUG(); it took us quite non-trivial time realize that the customer had force_remove enabled. Even if the BUG was removed here and we could propagate the error up the call chain it wouldn't help at all because then we would hit a crash or a memory corruption later and harder to debug. So force_remove is unfixable for the memory hotremove. We haven't checked other hotplugable resources to be prone to a similar problems. Remove the force_remove functionality because it is not fixable currently. Keep the sysfs file and report an error if somebody tries to enable it. Encourage users to report about the missing functionality and work with them with an alternative solution. Reviewed-by: Lee, Chun-Yi <jlee@suse.com> Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
/sys/firmware/acpi/hotplug/force_remove was presumably added to support
auto offlining in the past. This is, however, inherently dangerous for
some hotplugable resources like memory. The memory offlining fails when
the memory is still in use and cannot be dropped or migrated. If we
ignore the failure we are basically allowing for subtle memory
corruption or a crash.

We have actually noticed the later while hitting BUG() during the memory
hotremove (remove_memory):
	ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
			check_memblock_offlined_cb);
	if (ret)
		BUG();

it took us quite non-trivial time realize that the customer had
force_remove enabled. Even if the BUG was removed here and we could
propagate the error up the call chain it wouldn't help at all because
then we would hit a crash or a memory corruption later and harder to
debug. So force_remove is unfixable for the memory hotremove. We haven't
checked other hotplugable resources to be prone to a similar problems.

Remove the force_remove functionality because it is not fixable currently.
Keep the sysfs file and report an error if somebody tries to enable it.
Encourage users to report about the missing functionality and work with
them with an alternative solution.

Reviewed-by: Lee, Chun-Yi <jlee@suse.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
x86/ioapic: Split IOAPIC hot-removal into two steps 2017-03-01T09:51:41+00:00 Rui Wang rui.y.wang@intel.com 2017-02-28T13:34:29+00:00 f2ae5da726172fcf82f7be801489dd585f6a38eb The hot removal of IOAPIC is handling PCI and ACPI removal in one go. That only works when the PCI drivers released the interrupt resources, but breaks when a IOAPIC interrupt is still associated to a PCI device. The new pcibios_release_device() callback allows to solve that problem by splitting the removal into two steps: 1) PCI removal: Release all PCI resources including eventually not yet released IOAPIC interrupts via the new pcibios_release_device() callback. 2) ACPI removal: After release of all PCI resources the ACPI resources can be released without issue. [ tglx: Rewrote changelog ] Signed-off-by: Rui Wang <rui.y.wang@intel.com> Cc: tony.luck@intel.com Cc: linux-pci@vger.kernel.org Cc: rjw@rjwysocki.net Cc: linux-acpi@vger.kernel.org Cc: fengguang.wu@intel.com Cc: helgaas@kernel.org Cc: kbuild-all@01.org Cc: bhelgaas@google.com Link: http://lkml.kernel.org/r/1488288869-31290-3-git-send-email-rui.y.wang@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
The hot removal of IOAPIC is handling PCI and ACPI removal in one go. That
only works when the PCI drivers released the interrupt resources, but
breaks when a IOAPIC interrupt is still associated to a PCI device.

The new pcibios_release_device() callback allows to solve that problem by
splitting the removal into two steps:

1) PCI removal:

   Release all PCI resources including eventually not yet released IOAPIC
   interrupts via the new pcibios_release_device() callback.

2) ACPI removal:

   After release of all PCI resources the ACPI resources can be released
   without issue.

[ tglx: Rewrote changelog ]

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Cc: tony.luck@intel.com
Cc: linux-pci@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: linux-acpi@vger.kernel.org
Cc: fengguang.wu@intel.com
Cc: helgaas@kernel.org
Cc: kbuild-all@01.org
Cc: bhelgaas@google.com
Link: http://lkml.kernel.org/r/1488288869-31290-3-git-send-email-rui.y.wang@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
ACPI / EC: Use busy polling mode when GPE is not enabled 2017-01-30T11:12:52+00:00 Lv Zheng lv.zheng@intel.com 2017-01-20T08:42:48+00:00 c3a696b6e8f8f75f9f75e556a9f9f6472eae2655 When GPE is not enabled, it is not efficient to use the wait polling mode as it introduces an unexpected scheduler delay. So before the GPE handler is installed, this patch uses busy polling mode for all EC(s) and the logic can be applied to non boot EC(s) during the suspend/resume process. Link: https://bugzilla.kernel.org/show_bug.cgi?id=191561 Tested-by: Jakobus Schurz <jakobus.schurz@gmail.com> Tested-by: Chen Yu <yu.c.chen@intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
When GPE is not enabled, it is not efficient to use the wait polling mode
as it introduces an unexpected scheduler delay.
So before the GPE handler is installed, this patch uses busy polling mode
for all EC(s) and the logic can be applied to non boot EC(s) during the
suspend/resume process.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=191561
Tested-by: Jakobus Schurz <jakobus.schurz@gmail.com>
Tested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPI / sysfs: Provide quirk mechanism to prevent GPE flooding 2016-12-26T22:16:39+00:00 Lv Zheng lv.zheng@intel.com 2016-12-16T04:07:57+00:00 9c4aa1eecb48cfac18ed5e3aca9d9ae58fbafc11 Sometimes, the users may require a quirk to be provided from ACPI subsystem core to prevent a GPE from flooding. Normally, if a GPE cannot be dispatched, ACPICA core automatically prevents the GPE from firing. But there are cases the GPE is dispatched by _Lxx/_Exx provided via AML table, and OSPM is lacking of the knowledge to get _Lxx/_Exx correctly executed to handle the GPE, thus the GPE flooding may still occur. The existing quirk mechanism can be enabled/disabled using the following commands to prevent such kind of GPE flooding during runtime: # echo mask > /sys/firmware/acpi/interrupts/gpe00 # echo unmask > /sys/firmware/acpi/interrupts/gpe00 To avoid GPE flooding during boot, we need a boot stage mechanism. This patch provides such a boot stage quirk mechanism to stop this kind of GPE flooding. This patch doesn't fix any feature gap but since the new feature gaps could be found in the future endlessly, and can disappear if the feature gaps are filled, providing a boot parameter rather than a DMI table should suffice. Link: https://bugzilla.kernel.org/show_bug.cgi?id=53071 Link: https://bugzilla.kernel.org/show_bug.cgi?id=117481 Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/887793 Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Sometimes, the users may require a quirk to be provided from ACPI subsystem
core to prevent a GPE from flooding.
Normally, if a GPE cannot be dispatched, ACPICA core automatically prevents
the GPE from firing. But there are cases the GPE is dispatched by _Lxx/_Exx
provided via AML table, and OSPM is lacking of the knowledge to get
_Lxx/_Exx correctly executed to handle the GPE, thus the GPE flooding may
still occur.

The existing quirk mechanism can be enabled/disabled using the following
commands to prevent such kind of GPE flooding during runtime:
 # echo mask > /sys/firmware/acpi/interrupts/gpe00
 # echo unmask > /sys/firmware/acpi/interrupts/gpe00
To avoid GPE flooding during boot, we need a boot stage mechanism.

This patch provides such a boot stage quirk mechanism to stop this kind of
GPE flooding. This patch doesn't fix any feature gap but since the new
feature gaps could be found in the future endlessly, and can disappear if
the feature gaps are filled, providing a boot parameter rather than a DMI
table should suffice.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=53071
Link: https://bugzilla.kernel.org/show_bug.cgi?id=117481
Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/887793
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>