Documentation: ACPI: move acpi-lid.txt to firmware-guide/acpi and convert to reST

This converts the plain text documentation to reStructuredText format
and adds it to Sphinx TOC tree.

No essential content change.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 0 insertions, 96 deletions

diff --git a/Documentation/acpi/acpi-lid.txt b/Documentation/acpi/acpi-lid.txt
deleted file mode 100644
index effe7af3a5af..000000000000
--- a/Documentation/acpi/acpi-lid.txt
+++ /dev/null
@@ -1,96 +0,0 @@
-Special Usage Model of the ACPI Control Method Lid Device
-
-Copyright (C) 2016, Intel Corporation
-Author: Lv Zheng <lv.zheng@intel.com>
-
-
-Abstract:
-
-Platforms containing lids convey lid state (open/close) to OSPMs using a
-control method lid device. To implement this, the AML tables issue
-Notify(lid_device, 0x80) to notify the OSPMs whenever the lid state has
-changed. The _LID control method for the lid device must be implemented to
-report the "current" state of the lid as either "opened" or "closed".
-
-For most platforms, both the _LID method and the lid notifications are
-reliable. However, there are exceptions. In order to work with these
-exceptional buggy platforms, special restrictions and expections should be
-taken into account. This document describes the restrictions and the
-expections of the Linux ACPI lid device driver.
-
-
-1. Restrictions of the returning value of the _LID control method
-
-The _LID control method is described to return the "current" lid state.
-However the word of "current" has ambiguity, some buggy AML tables return
-the lid state upon the last lid notification instead of returning the lid
-state upon the last _LID evaluation. There won't be difference when the
-_LID control method is evaluated during the runtime, the problem is its
-initial returning value. When the AML tables implement this control method
-with cached value, the initial returning value is likely not reliable.
-There are platforms always retun "closed" as initial lid state.
-
-2. Restrictions of the lid state change notifications
-
-There are buggy AML tables never notifying when the lid device state is
-changed to "opened". Thus the "opened" notification is not guaranteed. But
-it is guaranteed that the AML tables always notify "closed" when the lid
-state is changed to "closed". The "closed" notification is normally used to
-trigger some system power saving operations on Windows. Since it is fully
-tested, it is reliable from all AML tables.
-
-3. Expections for the userspace users of the ACPI lid device driver
-
-The ACPI button driver exports the lid state to the userspace via the
-following file:
-  /proc/acpi/button/lid/LID0/state
-This file actually calls the _LID control method described above. And given
-the previous explanation, it is not reliable enough on some platforms. So
-it is advised for the userspace program to not to solely rely on this file
-to determine the actual lid state.
-
-The ACPI button driver emits the following input event to the userspace:
-  SW_LID
-The ACPI lid device driver is implemented to try to deliver the platform
-triggered events to the userspace. However, given the fact that the buggy
-firmware cannot make sure "opened"/"closed" events are paired, the ACPI
-button driver uses the following 3 modes in order not to trigger issues.
-
-If the userspace hasn't been prepared to ignore the unreliable "opened"
-events and the unreliable initial state notification, Linux users can use
-the following kernel parameters to handle the possible issues:
-A. button.lid_init_state=method:
-   When this option is specified, the ACPI button driver reports the
-   initial lid state using the returning value of the _LID control method
-   and whether the "opened"/"closed" events are paired fully relies on the
-   firmware implementation.
-   This option can be used to fix some platforms where the returning value
-   of the _LID control method is reliable but the initial lid state
-   notification is missing.
-   This option is the default behavior during the period the userspace
-   isn't ready to handle the buggy AML tables.
-B. button.lid_init_state=open:
-   When this option is specified, the ACPI button driver always reports the
-   initial lid state as "opened" and whether the "opened"/"closed" events
-   are paired fully relies on the firmware implementation.
-   This may fix some platforms where the returning value of the _LID
-   control method is not reliable and the initial lid state notification is
-   missing.
-
-If the userspace has been prepared to ignore the unreliable "opened" events
-and the unreliable initial state notification, Linux users should always
-use the following kernel parameter:
-C. button.lid_init_state=ignore:
-   When this option is specified, the ACPI button driver never reports the
-   initial lid state and there is a compensation mechanism implemented to
-   ensure that the reliable "closed" notifications can always be delievered
-   to the userspace by always pairing "closed" input events with complement
-   "opened" input events. But there is still no guarantee that the "opened"
-   notifications can be delivered to the userspace when the lid is actually
-   opens given that some AML tables do not send "opened" notifications
-   reliably.
-   In this mode, if everything is correctly implemented by the platform
-   firmware, the old userspace programs should still work. Otherwise, the
-   new userspace programs are required to work with the ACPI button driver.
-   This option will be the default behavior after the userspace is ready to
-   handle the buggy AML tables.