<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/drivers/acpi, branch v4.10-rc7</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>Merge tag 'acpi-4.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm</title>
<updated>2017-01-27T01:27:00+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-01-27T01:27:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2287a240a6b1c39fd06f94e57b8c0189c497efe5'/>
<id>2287a240a6b1c39fd06f94e57b8c0189c497efe5</id>
<content type='text'>
Pull ACPI fixes from Rafael Wysocki:
 "These fix two regressions introduced recently, one by reverting the
  problematic commit and one by fixing up locking in the ACPICA core.

  Specifics:

   - Revert a recent change that added an ACPI video blacklist entry for
     HP Pavilion dv6 as it turned to introduce backlight handling
     regressions on some systems (Hans de Goede).

   - Fix locking in the ACPICA core to avoid deadlocks related to table
     loading that were exposed by a recent change in that area (Lv
     Zheng)"

* tag 'acpi-4.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Revert "ACPI / video: Add force_native quirk for HP Pavilion dv6"
  ACPICA: Tables: Fix hidden logic related to acpi_tb_install_standard_table()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull ACPI fixes from Rafael Wysocki:
 "These fix two regressions introduced recently, one by reverting the
  problematic commit and one by fixing up locking in the ACPICA core.

  Specifics:

   - Revert a recent change that added an ACPI video blacklist entry for
     HP Pavilion dv6 as it turned to introduce backlight handling
     regressions on some systems (Hans de Goede).

   - Fix locking in the ACPICA core to avoid deadlocks related to table
     loading that were exposed by a recent change in that area (Lv
     Zheng)"

* tag 'acpi-4.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Revert "ACPI / video: Add force_native quirk for HP Pavilion dv6"
  ACPICA: Tables: Fix hidden logic related to acpi_tb_install_standard_table()
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branches 'acpica' and 'acpi-video'</title>
<updated>2017-01-26T23:39:02+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2017-01-26T23:39:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=0389227dde3abae442521948caf5c173e696cdca'/>
<id>0389227dde3abae442521948caf5c173e696cdca</id>
<content type='text'>
* acpica:
  ACPICA: Tables: Fix hidden logic related to acpi_tb_install_standard_table()

* acpi-video:
  Revert "ACPI / video: Add force_native quirk for HP Pavilion dv6"
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* acpica:
  ACPICA: Tables: Fix hidden logic related to acpi_tb_install_standard_table()

* acpi-video:
  Revert "ACPI / video: Add force_native quirk for HP Pavilion dv6"
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branches 'pm-sleep' and 'pm-cpufreq'</title>
<updated>2017-01-26T23:08:59+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2017-01-26T23:08:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=ff7e593c9cf3ccceaab7ac600cbd52cb9ff4c57a'/>
<id>ff7e593c9cf3ccceaab7ac600cbd52cb9ff4c57a</id>
<content type='text'>
* pm-sleep:
  Revert "PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag"

* pm-cpufreq:
  cpufreq: intel_pstate: Fix sysfs limits enforcement for performance policy
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* pm-sleep:
  Revert "PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag"

* pm-cpufreq:
  cpufreq: intel_pstate: Fix sysfs limits enforcement for performance policy
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "ACPI / video: Add force_native quirk for HP Pavilion dv6"</title>
<updated>2017-01-25T13:04:13+00:00</updated>
<author>
<name>Hans de Goede</name>
<email>hdegoede@redhat.com</email>
</author>
<published>2017-01-22T12:24:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=fd25ea29093e275195d0ae8b2573021a1c98959f'/>
<id>fd25ea29093e275195d0ae8b2573021a1c98959f</id>
<content type='text'>
Revert commit 6276e53fa8c0 (ACPI / video: Add force_native quirk for
HP Pavilion dv6).

In the commit message for the quirk this revert removes I wrote:

"Note that there are quite a few HP Pavilion dv6 variants, some
woth ATI and some with NVIDIA hybrid gfx, both seem to need this
quirk to have working backlight control. There are also some versions
with only Intel integrated gfx, these may not need this quirk, but it
should not hurt there."

Unfortunately that seems wrong, I've already received 2 reports of
this commit causing regressions on some dv6 variants (at least one
of which actually has a nvidia GPU). So it seems that HP has made a
mess here by using the same model-name both in marketing and in the
DMI data for many different variants. Some of which need
acpi_backlight=native for functional backlight control (as the
quirk this commit reverts was doing), where as others are broken by
it. So lets get back to the old sitation so as to avoid regressing
on models which used to work without any kernel cmdline arguments
before.

Fixes: 6276e53fa8c0 (ACPI / video: Add force_native quirk for HP Pavilion dv6)
Signed-off-by: Hans de Goede &lt;hdegoede@redhat.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Revert commit 6276e53fa8c0 (ACPI / video: Add force_native quirk for
HP Pavilion dv6).

In the commit message for the quirk this revert removes I wrote:

"Note that there are quite a few HP Pavilion dv6 variants, some
woth ATI and some with NVIDIA hybrid gfx, both seem to need this
quirk to have working backlight control. There are also some versions
with only Intel integrated gfx, these may not need this quirk, but it
should not hurt there."

Unfortunately that seems wrong, I've already received 2 reports of
this commit causing regressions on some dv6 variants (at least one
of which actually has a nvidia GPU). So it seems that HP has made a
mess here by using the same model-name both in marketing and in the
DMI data for many different variants. Some of which need
acpi_backlight=native for functional backlight control (as the
quirk this commit reverts was doing), where as others are broken by
it. So lets get back to the old sitation so as to avoid regressing
on models which used to work without any kernel cmdline arguments
before.

Fixes: 6276e53fa8c0 (ACPI / video: Add force_native quirk for HP Pavilion dv6)
Signed-off-by: Hans de Goede &lt;hdegoede@redhat.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPICA: Tables: Fix hidden logic related to acpi_tb_install_standard_table()</title>
<updated>2017-01-20T02:44:58+00:00</updated>
<author>
<name>Lv Zheng</name>
<email>lv.zheng@intel.com</email>
</author>
<published>2017-01-19T07:21:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=7a37052adb5e843bcfff6c98aee9b60bb087b910'/>
<id>7a37052adb5e843bcfff6c98aee9b60bb087b910</id>
<content type='text'>
There is a hidden logic for acpi_tb_install_standard_table() as it can be
invoked from the boot stage and during runtime.

 1. When it is invoked from the OS boot stage, the ACPICA mutex may not have
    been initialized yet and so acpi_ut_acquire_mutex()/acpi_ut_release_mutex()
    are not invoked in these code paths:

   acpi_initialize_tables
     acpi_tb_parse_root_table
       acpi_tb_install_standard_table (4 invocations)
   acpi_install_table
       acpi_tb_install_standard_table

 2. When it is invoked during the runtime, ACPICA mutex is used as
    appropriate:

   acpi_ex_load_op
     acpi_tb_install_and_load_table
       acpi_tb_install_standard_table
   acpi_load_table
     acpi_tb_install_and_load_table
       acpi_tb_install_standard_table

The mutex is now used in acpi_tb_install_and_load_table(), while it actually
should be in acpi_tb_install_standard_table().

This introduces another problem in acpi_tb_install_standard_table() where
acpi_gbl_table_handler is invoked from and the lock contexts are thus not
consistent for the table handlers. This triggers a regression when
acpi_get_table()/acpi_put_table() start to hold table mutex during runtime.

The regression is noticed by LKP as new errors reported by ACPICA mutex
debugging facility.

[    2.043693] ACPI Error: Mutex [ACPI_MTX_Tables] already acquired by this thread [497483776] (20160930/utmutex-254)
[    2.054084] ACPI Error: Mutex [0x2] is not acquired, cannot release (20160930/utmutex-326)

And it triggers a deadlock:

[  247.066214] INFO: task swapper/0:1 blocked for more than 120 seconds.
...
[  247.091271] Call Trace:
...
[  247.121523]  down_timeout+0x47/0x50
[  247.125065]  acpi_os_wait_semaphore+0x47/0x62
[  247.129475]  acpi_ut_acquire_mutex+0x43/0x81
[  247.133798]  acpi_get_table+0x2d/0x84
[  247.137513]  acpi_table_attr_init+0xcd/0x100
[  247.146590]  acpi_sysfs_table_handler+0x5d/0xb8
[  247.151174]  acpi_bus_table_handler+0x23/0x2a
[  247.155583]  acpi_tb_install_standard_table+0xe0/0x213
[  247.164489]  acpi_tb_install_and_load_table+0x3a/0x82
[  247.169592]  acpi_ex_load_op+0x194/0x201
...
[  247.200108]  acpi_ns_evaluate+0x1bb/0x247
[  247.204170]  acpi_evaluate_object+0x178/0x274
[  247.213249]  acpi_processor_set_pdc+0x154/0x17b
...
The table mutex is held in acpi_tb_install_and_load_table() and is re-visited by
acpi_get_table().

Noticing that the early mutex requirement actually belongs to the OSL layer
and has already been handled in acpi_os_wait_semaphore()/acpi_os_signal_semaphore(),
the regression canbe fixed by removing this hidden logic from the ACPICA core
to the OS-specific code.

Fixes: 174cc7187e6f ("ACPICA: Tables: Back port acpi_get_table_with_size() and early_acpi_os_unmap_memory() from Linux kernel")
Reported-and-tested-by: Tomi Sarvela &lt;tomi.p.sarvela@intel.com&gt;
Reported-by: Ye Xiaolong &lt;xiaolong.ye@intel.com&gt;
Signed-off-by: Lv Zheng &lt;lv.zheng@intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There is a hidden logic for acpi_tb_install_standard_table() as it can be
invoked from the boot stage and during runtime.

 1. When it is invoked from the OS boot stage, the ACPICA mutex may not have
    been initialized yet and so acpi_ut_acquire_mutex()/acpi_ut_release_mutex()
    are not invoked in these code paths:

   acpi_initialize_tables
     acpi_tb_parse_root_table
       acpi_tb_install_standard_table (4 invocations)
   acpi_install_table
       acpi_tb_install_standard_table

 2. When it is invoked during the runtime, ACPICA mutex is used as
    appropriate:

   acpi_ex_load_op
     acpi_tb_install_and_load_table
       acpi_tb_install_standard_table
   acpi_load_table
     acpi_tb_install_and_load_table
       acpi_tb_install_standard_table

The mutex is now used in acpi_tb_install_and_load_table(), while it actually
should be in acpi_tb_install_standard_table().

This introduces another problem in acpi_tb_install_standard_table() where
acpi_gbl_table_handler is invoked from and the lock contexts are thus not
consistent for the table handlers. This triggers a regression when
acpi_get_table()/acpi_put_table() start to hold table mutex during runtime.

The regression is noticed by LKP as new errors reported by ACPICA mutex
debugging facility.

[    2.043693] ACPI Error: Mutex [ACPI_MTX_Tables] already acquired by this thread [497483776] (20160930/utmutex-254)
[    2.054084] ACPI Error: Mutex [0x2] is not acquired, cannot release (20160930/utmutex-326)

And it triggers a deadlock:

[  247.066214] INFO: task swapper/0:1 blocked for more than 120 seconds.
...
[  247.091271] Call Trace:
...
[  247.121523]  down_timeout+0x47/0x50
[  247.125065]  acpi_os_wait_semaphore+0x47/0x62
[  247.129475]  acpi_ut_acquire_mutex+0x43/0x81
[  247.133798]  acpi_get_table+0x2d/0x84
[  247.137513]  acpi_table_attr_init+0xcd/0x100
[  247.146590]  acpi_sysfs_table_handler+0x5d/0xb8
[  247.151174]  acpi_bus_table_handler+0x23/0x2a
[  247.155583]  acpi_tb_install_standard_table+0xe0/0x213
[  247.164489]  acpi_tb_install_and_load_table+0x3a/0x82
[  247.169592]  acpi_ex_load_op+0x194/0x201
...
[  247.200108]  acpi_ns_evaluate+0x1bb/0x247
[  247.204170]  acpi_evaluate_object+0x178/0x274
[  247.213249]  acpi_processor_set_pdc+0x154/0x17b
...
The table mutex is held in acpi_tb_install_and_load_table() and is re-visited by
acpi_get_table().

Noticing that the early mutex requirement actually belongs to the OSL layer
and has already been handled in acpi_os_wait_semaphore()/acpi_os_signal_semaphore(),
the regression canbe fixed by removing this hidden logic from the ACPICA core
to the OS-specific code.

Fixes: 174cc7187e6f ("ACPICA: Tables: Back port acpi_get_table_with_size() and early_acpi_os_unmap_memory() from Linux kernel")
Reported-and-tested-by: Tomi Sarvela &lt;tomi.p.sarvela@intel.com&gt;
Reported-by: Ye Xiaolong &lt;xiaolong.ye@intel.com&gt;
Signed-off-by: Lv Zheng &lt;lv.zheng@intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag"</title>
<updated>2017-01-20T02:33:57+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2017-01-20T02:25:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e326ce013a8e851193eb337aafb1aa396c533a61'/>
<id>e326ce013a8e851193eb337aafb1aa396c533a61</id>
<content type='text'>
Revert commit 08b98d329165 (PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0
flag) as it caused system suspend (in the default configuration) to fail
on Dell XPS13 (9360) with the Kaby Lake processor.

Fixes: 08b98d329165 (PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag)
Reported-by: Paul Menzel &lt;pmenzel@molgen.mpg.de&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Revert commit 08b98d329165 (PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0
flag) as it caused system suspend (in the default configuration) to fail
on Dell XPS13 (9360) with the Kaby Lake processor.

Fixes: 08b98d329165 (PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag)
Reported-by: Paul Menzel &lt;pmenzel@molgen.mpg.de&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branches 'acpi-scan', 'acpi-sysfs', 'acpi-wdat' and 'acpi-tables'</title>
<updated>2017-01-06T13:36:30+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2017-01-06T13:36:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f1dabf0b0975f9e71344b5c8c0ab39c4d58d9274'/>
<id>f1dabf0b0975f9e71344b5c8c0ab39c4d58d9274</id>
<content type='text'>
* acpi-scan:
  ACPI / scan: Prefer devices without _HID/_CID for _ADR matching
  ACPI: Drop misplaced acpi_dma_deconfigure() call from acpi_bind_one()

* acpi-sysfs:
  ACPI / sysfs: Provide quirk mechanism to prevent GPE flooding

* acpi-wdat:
  ACPI / watchdog: Print out error number when device creation fails

* acpi-tables:
  ACPI / DMAR: Avoid passing NULL to acpi_put_table()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* acpi-scan:
  ACPI / scan: Prefer devices without _HID/_CID for _ADR matching
  ACPI: Drop misplaced acpi_dma_deconfigure() call from acpi_bind_one()

* acpi-sysfs:
  ACPI / sysfs: Provide quirk mechanism to prevent GPE flooding

* acpi-wdat:
  ACPI / watchdog: Print out error number when device creation fails

* acpi-tables:
  ACPI / DMAR: Avoid passing NULL to acpi_put_table()
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / scan: Prefer devices without _HID/_CID for _ADR matching</title>
<updated>2017-01-02T21:21:59+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2016-12-30T01:27:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=c2a6bbaf0c5f90463a7011a295bbdb7e33c80b51'/>
<id>c2a6bbaf0c5f90463a7011a295bbdb7e33c80b51</id>
<content type='text'>
The way acpi_find_child_device() works currently is that, if there
are two (or more) devices with the same _ADR value in the same
namespace scope (which is not specifically allowed by the spec and
the OS behavior in that case is not defined), the first one of them
found to be present (with the help of _STA) will be returned.

This covers the majority of cases, but is not sufficient if some of
the devices in question have a _HID (or _CID) returning some valid
ACPI/PNP device IDs (which is disallowed by the spec) and the
ASL writers' expectation appears to be that the OS will match
devices without a valid ACPI/PNP device ID against a given bus
address first.

To cover this special case as well, modify find_child_checks()
to prefer devices without ACPI/PNP device IDs over devices that
have them.

Suggested-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Tested-by: Hans de Goede &lt;hdegoede@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The way acpi_find_child_device() works currently is that, if there
are two (or more) devices with the same _ADR value in the same
namespace scope (which is not specifically allowed by the spec and
the OS behavior in that case is not defined), the first one of them
found to be present (with the help of _STA) will be returned.

This covers the majority of cases, but is not sufficient if some of
the devices in question have a _HID (or _CID) returning some valid
ACPI/PNP device IDs (which is disallowed by the spec) and the
ASL writers' expectation appears to be that the OS will match
devices without a valid ACPI/PNP device ID against a given bus
address first.

To cover this special case as well, modify find_child_checks()
to prefer devices without ACPI/PNP device IDs over devices that
have them.

Suggested-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Tested-by: Hans de Goede &lt;hdegoede@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / watchdog: Print out error number when device creation fails</title>
<updated>2016-12-26T22:21:56+00:00</updated>
<author>
<name>Mika Westerberg</name>
<email>mika.westerberg@linux.intel.com</email>
</author>
<published>2016-12-22T10:17:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=c6e2c1e1138fa5cb5bb99381132855bbaf712029'/>
<id>c6e2c1e1138fa5cb5bb99381132855bbaf712029</id>
<content type='text'>
If the platform device creation fails for whichever reason the driver
prints out something like:

  [    0.978837] ACPI: watchdog: Failed to create platform device

However, that is quite confusing and does not include any information
why it failed. To make it more understandable, reword it like:

  [    0.978837] ACPI: watchdog: Device creation failed: -16

Which tells that we failed to create the watchdog device because some of
the resources were already reserved (-EBUSY).

Signed-off-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If the platform device creation fails for whichever reason the driver
prints out something like:

  [    0.978837] ACPI: watchdog: Failed to create platform device

However, that is quite confusing and does not include any information
why it failed. To make it more understandable, reword it like:

  [    0.978837] ACPI: watchdog: Device creation failed: -16

Which tells that we failed to create the watchdog device because some of
the resources were already reserved (-EBUSY).

Signed-off-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI / sysfs: Provide quirk mechanism to prevent GPE flooding</title>
<updated>2016-12-26T22:16:39+00:00</updated>
<author>
<name>Lv Zheng</name>
<email>lv.zheng@intel.com</email>
</author>
<published>2016-12-16T04:07:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=9c4aa1eecb48cfac18ed5e3aca9d9ae58fbafc11'/>
<id>9c4aa1eecb48cfac18ed5e3aca9d9ae58fbafc11</id>
<content type='text'>
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 &gt; /sys/firmware/acpi/interrupts/gpe00
 # echo unmask &gt; /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 &lt;lv.zheng@intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &gt; /sys/firmware/acpi/interrupts/gpe00
 # echo unmask &gt; /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 &lt;lv.zheng@intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
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