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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-06-28 13:00:45 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-06-28 13:00:45 +0200
commite8b6cb3947430d62538d88f615c007a51aeb23fe (patch)
tree9a5c4f74b59584a8763dc48ba296b72853d385ac /Documentation
parentbdc8f09685a25a12f2f5282f56672ba663ecb88c (diff)
parent73e797f79e5edb3d000d1911a2d859f15c446c1a (diff)
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Merge branch 'acpi-doc'
* acpi-doc: Documentation / CPU hotplug: Rephrase the outdated description for MADT entries ACPI / video: update video_extension.txt for backlight control ACPI / video: move video_extension.txt to Documentation/acpi ACPI / video: add description for brightness_switch_enabled ACPI: Add ACPI namespace documentation ACPI: Add sysfs ABI documentation ACPI: Update MAINTAINERS file to include Documentation/acpi
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-bus-acpi58
-rw-r--r--Documentation/ABI/testing/sysfs-devices-sun2
-rw-r--r--Documentation/acpi/namespace.txt395
-rw-r--r--Documentation/acpi/video_extension.txt106
-rw-r--r--Documentation/cpu-hotplug.txt6
-rw-r--r--Documentation/kernel-parameters.txt9
-rw-r--r--Documentation/power/video_extension.txt37
7 files changed, 573 insertions, 40 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-acpi b/Documentation/ABI/testing/sysfs-bus-acpi
new file mode 100644
index 000000000000..7fa9cbc75344
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-acpi
@@ -0,0 +1,58 @@
+What: /sys/bus/acpi/devices/.../path
+Date: December 2006
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ This attribute indicates the full path of ACPI namespace
+ object associated with the device object. For example,
+ \_SB_.PCI0.
+ This file is not present for device objects representing
+ fixed ACPI hardware features (like power and sleep
+ buttons).
+
+What: /sys/bus/acpi/devices/.../modalias
+Date: July 2007
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ This attribute indicates the PNP IDs of the device object.
+ That is acpi:HHHHHHHH:[CCCCCCC:]. Where each HHHHHHHH or
+ CCCCCCCC contains device object's PNPID (_HID or _CID).
+
+What: /sys/bus/acpi/devices/.../hid
+Date: April 2005
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ This attribute indicates the hardware ID (_HID) of the
+ device object. For example, PNP0103.
+ This file is present for device objects having the _HID
+ control method.
+
+What: /sys/bus/acpi/devices/.../description
+Date: October 2012
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ This attribute contains the output of the device object's
+ _STR control method, if present.
+
+What: /sys/bus/acpi/devices/.../adr
+Date: October 2012
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ This attribute contains the output of the device object's
+ _ADR control method, which is present for ACPI device
+ objects representing devices having standard enumeration
+ algorithms, such as PCI.
+
+What: /sys/bus/acpi/devices/.../uid
+Date: October 2012
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ This attribute contains the output of the device object's
+ _UID control method, if present.
+
+What: /sys/bus/acpi/devices/.../eject
+Date: December 2006
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ Writing 1 to this attribute will trigger hot removal of
+ this device object. This file exists for every device
+ object that has _EJ0 method.
diff --git a/Documentation/ABI/testing/sysfs-devices-sun b/Documentation/ABI/testing/sysfs-devices-sun
index 86be9848a77e..625ce4b63758 100644
--- a/Documentation/ABI/testing/sysfs-devices-sun
+++ b/Documentation/ABI/testing/sysfs-devices-sun
@@ -1,4 +1,4 @@
-Whatt: /sys/devices/.../sun
+What: /sys/devices/.../sun
Date: October 2012
Contact: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Description:
diff --git a/Documentation/acpi/namespace.txt b/Documentation/acpi/namespace.txt
new file mode 100644
index 000000000000..260f6a3661fa
--- /dev/null
+++ b/Documentation/acpi/namespace.txt
@@ -0,0 +1,395 @@
+ACPI Device Tree - Representation of ACPI Namespace
+
+Copyright (C) 2013, Intel Corporation
+Author: Lv Zheng <lv.zheng@intel.com>
+
+
+Abstract:
+
+The Linux ACPI subsystem converts ACPI namespace objects into a Linux
+device tree under the /sys/devices/LNXSYSTEM:00 and updates it upon
+receiving ACPI hotplug notification events. For each device object in this
+hierarchy there is a corresponding symbolic link in the
+/sys/bus/acpi/devices.
+This document illustrates the structure of the ACPI device tree.
+
+
+Credit:
+
+Thanks for the help from Zhang Rui <rui.zhang@intel.com> and Rafael J.
+Wysocki <rafael.j.wysocki@intel.com>.
+
+
+1. ACPI Definition Blocks
+
+ The ACPI firmware sets up RSDP (Root System Description Pointer) in the
+ system memory address space pointing to the XSDT (Extended System
+ Description Table). The XSDT always points to the FADT (Fixed ACPI
+ Description Table) using its first entry, the data within the FADT
+ includes various fixed-length entries that describe fixed ACPI features
+ of the hardware. The FADT contains a pointer to the DSDT
+ (Differentiated System Descripition Table). The XSDT also contains
+ entries pointing to possibly multiple SSDTs (Secondary System
+ Description Table).
+
+ The DSDT and SSDT data is organized in data structures called definition
+ blocks that contain definitions of various objects, including ACPI
+ control methods, encoded in AML (ACPI Machine Language). The data block
+ of the DSDT along with the contents of SSDTs represents a hierarchical
+ data structure called the ACPI namespace whose topology reflects the
+ structure of the underlying hardware platform.
+
+ The relationships between ACPI System Definition Tables described above
+ are illustrated in the following diagram.
+
+ +---------+ +-------+ +--------+ +------------------------+
+ | RSDP | +->| XSDT | +->| FADT | | +-------------------+ |
+ +---------+ | +-------+ | +--------+ +-|->| DSDT | |
+ | Pointer | | | Entry |-+ | ...... | | | +-------------------+ |
+ +---------+ | +-------+ | X_DSDT |--+ | | Definition Blocks | |
+ | Pointer |-+ | ..... | | ...... | | +-------------------+ |
+ +---------+ +-------+ +--------+ | +-------------------+ |
+ | Entry |------------------|->| SSDT | |
+ +- - - -+ | +-------------------| |
+ | Entry | - - - - - - - -+ | | Definition Blocks | |
+ +- - - -+ | | +-------------------+ |
+ | | +- - - - - - - - - -+ |
+ +-|->| SSDT | |
+ | +-------------------+ |
+ | | Definition Blocks | |
+ | +- - - - - - - - - -+ |
+ +------------------------+
+ |
+ OSPM Loading |
+ \|/
+ +----------------+
+ | ACPI Namespace |
+ +----------------+
+
+ Figure 1. ACPI Definition Blocks
+
+ NOTE: RSDP can also contain a pointer to the RSDT (Root System
+ Description Table). Platforms provide RSDT to enable
+ compatibility with ACPI 1.0 operating systems. The OS is expected
+ to use XSDT, if present.
+
+
+2. Example ACPI Namespace
+
+ All definition blocks are loaded into a single namespace. The namespace
+ is a hierarchy of objects identified by names and paths.
+ The following naming conventions apply to object names in the ACPI
+ namespace:
+ 1. All names are 32 bits long.
+ 2. The first byte of a name must be one of 'A' - 'Z', '_'.
+ 3. Each of the remaining bytes of a name must be one of 'A' - 'Z', '0'
+ - '9', '_'.
+ 4. Names starting with '_' are reserved by the ACPI specification.
+ 5. The '\' symbol represents the root of the namespace (i.e. names
+ prepended with '\' are relative to the namespace root).
+ 6. The '^' symbol represents the parent of the current namespace node
+ (i.e. names prepended with '^' are relative to the parent of the
+ current namespace node).
+
+ The figure below shows an example ACPI namespace.
+
+ +------+
+ | \ | Root
+ +------+
+ |
+ | +------+
+ +-| _PR | Scope(_PR): the processor namespace
+ | +------+
+ | |
+ | | +------+
+ | +-| CPU0 | Processor(CPU0): the first processor
+ | +------+
+ |
+ | +------+
+ +-| _SB | Scope(_SB): the system bus namespace
+ | +------+
+ | |
+ | | +------+
+ | +-| LID0 | Device(LID0); the lid device
+ | | +------+
+ | | |
+ | | | +------+
+ | | +-| _HID | Name(_HID, "PNP0C0D"): the hardware ID
+ | | | +------+
+ | | |
+ | | | +------+
+ | | +-| _STA | Method(_STA): the status control method
+ | | +------+
+ | |
+ | | +------+
+ | +-| PCI0 | Device(PCI0); the PCI root bridge
+ | +------+
+ | |
+ | | +------+
+ | +-| _HID | Name(_HID, "PNP0A08"): the hardware ID
+ | | +------+
+ | |
+ | | +------+
+ | +-| _CID | Name(_CID, "PNP0A03"): the compatible ID
+ | | +------+
+ | |
+ | | +------+
+ | +-| RP03 | Scope(RP03): the PCI0 power scope
+ | | +------+
+ | | |
+ | | | +------+
+ | | +-| PXP3 | PowerResource(PXP3): the PCI0 power resource
+ | | +------+
+ | |
+ | | +------+
+ | +-| GFX0 | Device(GFX0): the graphics adapter
+ | +------+
+ | |
+ | | +------+
+ | +-| _ADR | Name(_ADR, 0x00020000): the PCI bus address
+ | | +------+
+ | |
+ | | +------+
+ | +-| DD01 | Device(DD01): the LCD output device
+ | +------+
+ | |
+ | | +------+
+ | +-| _BCL | Method(_BCL): the backlight control method
+ | +------+
+ |
+ | +------+
+ +-| _TZ | Scope(_TZ): the thermal zone namespace
+ | +------+
+ | |
+ | | +------+
+ | +-| FN00 | PowerResource(FN00): the FAN0 power resource
+ | | +------+
+ | |
+ | | +------+
+ | +-| FAN0 | Device(FAN0): the FAN0 cooling device
+ | | +------+
+ | | |
+ | | | +------+
+ | | +-| _HID | Name(_HID, "PNP0A0B"): the hardware ID
+ | | +------+
+ | |
+ | | +------+
+ | +-| TZ00 | ThermalZone(TZ00); the FAN thermal zone
+ | +------+
+ |
+ | +------+
+ +-| _GPE | Scope(_GPE): the GPE namespace
+ +------+
+
+ Figure 2. Example ACPI Namespace
+
+
+3. Linux ACPI Device Objects
+
+ The Linux kernel's core ACPI subsystem creates struct acpi_device
+ objects for ACPI namespace objects representing devices, power resources
+ processors, thermal zones. Those objects are exported to user space via
+ sysfs as directories in the subtree under /sys/devices/LNXSYSTM:00. The
+ format of their names is <bus_id:instance>, where 'bus_id' refers to the
+ ACPI namespace representation of the given object and 'instance' is used
+ for distinguishing different object of the same 'bus_id' (it is
+ two-digit decimal representation of an unsigned integer).
+
+ The value of 'bus_id' depends on the type of the object whose name it is
+ part of as listed in the table below.
+
+ +---+-----------------+-------+----------+
+ | | Object/Feature | Table | bus_id |
+ +---+-----------------+-------+----------+
+ | N | Root | xSDT | LNXSYSTM |
+ +---+-----------------+-------+----------+
+ | N | Device | xSDT | _HID |
+ +---+-----------------+-------+----------+
+ | N | Processor | xSDT | LNXCPU |
+ +---+-----------------+-------+----------+
+ | N | ThermalZone | xSDT | LNXTHERM |
+ +---+-----------------+-------+----------+
+ | N | PowerResource | xSDT | LNXPOWER |
+ +---+-----------------+-------+----------+
+ | N | Other Devices | xSDT | device |
+ +---+-----------------+-------+----------+
+ | F | PWR_BUTTON | FADT | LNXPWRBN |
+ +---+-----------------+-------+----------+
+ | F | SLP_BUTTON | FADT | LNXSLPBN |
+ +---+-----------------+-------+----------+
+ | M | Video Extension | xSDT | LNXVIDEO |
+ +---+-----------------+-------+----------+
+ | M | ATA Controller | xSDT | LNXIOBAY |
+ +---+-----------------+-------+----------+
+ | M | Docking Station | xSDT | LNXDOCK |
+ +---+-----------------+-------+----------+
+
+ Table 1. ACPI Namespace Objects Mapping
+
+ The following rules apply when creating struct acpi_device objects on
+ the basis of the contents of ACPI System Description Tables (as
+ indicated by the letter in the first column and the notation in the
+ second column of the table above):
+ N:
+ The object's source is an ACPI namespace node (as indicated by the
+ named object's type in the second column). In that case the object's
+ directory in sysfs will contain the 'path' attribute whose value is
+ the full path to the node from the namespace root.
+ struct acpi_device objects are created for the ACPI namespace nodes
+ whose _STA control methods return PRESENT or FUNCTIONING. The power
+ resource nodes or nodes without _STA are assumed to be both PRESENT
+ and FUNCTIONING.
+ F:
+ The struct acpi_device object is created for a fixed hardware
+ feature (as indicated by the fixed feature flag's name in the second
+ column), so its sysfs directory will not contain the 'path'
+ attribute.
+ M:
+ The struct acpi_device object is created for an ACPI namespace node
+ with specific control methods (as indicated by the ACPI defined
+ device's type in the second column). The 'path' attribute containing
+ its namespace path will be present in its sysfs directory. For
+ example, if the _BCL method is present for an ACPI namespace node, a
+ struct acpi_device object with LNXVIDEO 'bus_id' will be created for
+ it.
+
+ The third column of the above table indicates which ACPI System
+ Description Tables contain information used for the creation of the
+ struct acpi_device objects represented by the given row (xSDT means DSDT
+ or SSDT).
+
+ The forth column of the above table indicates the 'bus_id' generation
+ rule of the struct acpi_device object:
+ _HID:
+ _HID in the last column of the table means that the object's bus_id
+ is derived from the _HID/_CID identification objects present under
+ the corresponding ACPI namespace node. The object's sysfs directory
+ will then contain the 'hid' and 'modalias' attributes that can be
+ used to retrieve the _HID and _CIDs of that object.
+ LNXxxxxx:
+ The 'modalias' attribute is also present for struct acpi_device
+ objects having bus_id of the "LNXxxxxx" form (pseudo devices), in
+ which cases it contains the bus_id string itself.
+ device:
+ 'device' in the last column of the table indicates that the object's
+ bus_id cannot be determined from _HID/_CID of the corresponding
+ ACPI namespace node, although that object represents a device (for
+ example, it may be a PCI device with _ADR defined and without _HID
+ or _CID). In that case the string 'device' will be used as the
+ object's bus_id.
+
+
+4. Linux ACPI Physical Device Glue
+
+ ACPI device (i.e. struct acpi_device) objects may be linked to other
+ objects in the Linux' device hierarchy that represent "physical" devices
+ (for example, devices on the PCI bus). If that happens, it means that
+ the ACPI device object is a "companion" of a device otherwise
+ represented in a different way and is used (1) to provide configuration
+ information on that device which cannot be obtained by other means and
+ (2) to do specific things to the device with the help of its ACPI
+ control methods. One ACPI device object may be linked this way to
+ multiple "physical" devices.
+
+ If an ACPI device object is linked to a "physical" device, its sysfs
+ directory contains the "physical_node" symbolic link to the sysfs
+ directory of the target device object. In turn, the target device's
+ sysfs directory will then contain the "firmware_node" symbolic link to
+ the sysfs directory of the companion ACPI device object.
+ The linking mechanism relies on device identification provided by the
+ ACPI namespace. For example, if there's an ACPI namespace object
+ representing a PCI device (i.e. a device object under an ACPI namespace
+ object representing a PCI bridge) whose _ADR returns 0x00020000 and the
+ bus number of the parent PCI bridge is 0, the sysfs directory
+ representing the struct acpi_device object created for that ACPI
+ namespace object will contain the 'physical_node' symbolic link to the
+ /sys/devices/pci0000:00/0000:00:02:0/ sysfs directory of the
+ corresponding PCI device.
+
+ The linking mechanism is generally bus-specific. The core of its
+ implementation is located in the drivers/acpi/glue.c file, but there are
+ complementary parts depending on the bus types in question located
+ elsewhere. For example, the PCI-specific part of it is located in
+ drivers/pci/pci-acpi.c.
+
+
+5. Example Linux ACPI Device Tree
+
+ The sysfs hierarchy of struct acpi_device objects corresponding to the
+ example ACPI namespace illustrated in Figure 2 with the addition of
+ fixed PWR_BUTTON/SLP_BUTTON devices is shown below.
+
+ +--------------+---+-----------------+
+ | LNXSYSTEM:00 | \ | acpi:LNXSYSTEM: |
+ +--------------+---+-----------------+
+ |
+ | +-------------+-----+----------------+
+ +-| LNXPWRBN:00 | N/A | acpi:LNXPWRBN: |
+ | +-------------+-----+----------------+
+ |
+ | +-------------+-----+----------------+
+ +-| LNXSLPBN:00 | N/A | acpi:LNXSLPBN: |
+ | +-------------+-----+----------------+
+ |
+ | +-----------+------------+--------------+
+ +-| LNXCPU:00 | \_PR_.CPU0 | acpi:LNXCPU: |
+ | +-----------+------------+--------------+
+ |
+ | +-------------+-------+----------------+
+ +-| LNXSYBUS:00 | \_SB_ | acpi:LNXSYBUS: |
+ | +-------------+-------+----------------+
+ | |
+ | | +- - - - - - - +- - - - - - +- - - - - - - -+
+ | +-| * PNP0C0D:00 | \_SB_.LID0 | acpi:PNP0C0D: |
+ | | +- - - - - - - +- - - - - - +- - - - - - - -+
+ | |
+ | | +------------+------------+-----------------------+
+ | +-| PNP0A08:00 | \_SB_.PCI0 | acpi:PNP0A08:PNP0A03: |
+ | +------------+------------+-----------------------+
+ | |
+ | | +-----------+-----------------+-----+
+ | +-| device:00 | \_SB_.PCI0.RP03 | N/A |
+ | | +-----------+-----------------+-----+
+ | | |
+ | | | +-------------+----------------------+----------------+
+ | | +-| LNXPOWER:00 | \_SB_.PCI0.RP03.PXP3 | acpi:LNXPOWER: |
+ | | +-------------+----------------------+----------------+
+ | |
+ | | +-------------+-----------------+----------------+
+ | +-| LNXVIDEO:00 | \_SB_.PCI0.GFX0 | acpi:LNXVIDEO: |
+ | +-------------+-----------------+----------------+
+ | |
+ | | +-----------+-----------------+-----+
+ | +-| device:01 | \_SB_.PCI0.DD01 | N/A |
+ | +-----------+-----------------+-----+
+ |
+ | +-------------+-------+----------------+
+ +-| LNXSYBUS:01 | \_TZ_ | acpi:LNXSYBUS: |
+ +-------------+-------+----------------+
+ |
+ | +-------------+------------+----------------+
+ +-| LNXPOWER:0a | \_TZ_.FN00 | acpi:LNXPOWER: |
+ | +-------------+------------+----------------+
+ |
+ | +------------+------------+---------------+
+ +-| PNP0C0B:00 | \_TZ_.FAN0 | acpi:PNP0C0B: |
+ | +------------+------------+---------------+
+ |
+ | +-------------+------------+----------------+
+ +-| LNXTHERM:00 | \_TZ_.TZ00 | acpi:LNXTHERM: |
+ +-------------+------------+----------------+
+
+ Figure 3. Example Linux ACPI Device Tree
+
+ NOTE: Each node is represented as "object/path/modalias", where:
+ 1. 'object' is the name of the object's directory in sysfs.
+ 2. 'path' is the ACPI namespace path of the corresponding
+ ACPI namespace object, as returned by the object's 'path'
+ sysfs attribute.
+ 3. 'modalias' is the value of the object's 'modalias' sysfs
+ attribute (as described earlier in this document).
+ NOTE: N/A indicates the device object does not have the 'path' or the
+ 'modalias' attribute.
+ NOTE: The PNP0C0D device listed above is highlighted (marked by "*")
+ to indicate it will be created only when its _STA methods return
+ PRESENT or FUNCTIONING.
diff --git a/Documentation/acpi/video_extension.txt b/Documentation/acpi/video_extension.txt
new file mode 100644
index 000000000000..78b32ac02466
--- /dev/null
+++ b/Documentation/acpi/video_extension.txt
@@ -0,0 +1,106 @@
+ACPI video extensions
+~~~~~~~~~~~~~~~~~~~~~
+
+This driver implement the ACPI Extensions For Display Adapters for
+integrated graphics devices on motherboard, as specified in ACPI 2.0
+Specification, Appendix B, allowing to perform some basic control like
+defining the video POST device, retrieving EDID information or to
+setup a video output, etc. Note that this is an ref. implementation
+only. It may or may not work for your integrated video device.
+
+The ACPI video driver does 3 things regarding backlight control:
+
+1 Export a sysfs interface for user space to control backlight level
+
+If the ACPI table has a video device, and acpi_backlight=vendor kernel
+command line is not present, the driver will register a backlight device
+and set the required backlight operation structure for it for the sysfs
+interface control. For every registered class device, there will be a
+directory named acpi_videoX under /sys/class/backlight.
+
+The backlight sysfs interface has a standard definition here:
+Documentation/ABI/stable/sysfs-class-backlight.
+
+And what ACPI video driver does is:
+actual_brightness: on read, control method _BQC will be evaluated to
+get the brightness level the firmware thinks it is at;
+bl_power: not implemented, will set the current brightness instead;
+brightness: on write, control method _BCM will run to set the requested
+brightness level;
+max_brightness: Derived from the _BCL package(see below);
+type: firmware
+
+Note that ACPI video backlight driver will always use index for
+brightness, actual_brightness and max_brightness. So if we have
+the following _BCL package:
+
+Method (_BCL, 0, NotSerialized)
+{
+ Return (Package (0x0C)
+ {
+ 0x64,
+ 0x32,
+ 0x0A,
+ 0x14,
+ 0x1E,
+ 0x28,
+ 0x32,
+ 0x3C,
+ 0x46,
+ 0x50,
+ 0x5A,
+ 0x64
+ })
+}
+
+The first two levels are for when laptop are on AC or on battery and are
+not used by Linux currently. The remaining 10 levels are supported levels
+that we can choose from. The applicable index values are from 0 (that
+corresponds to the 0x0A brightness value) to 9 (that corresponds to the
+0x64 brightness value) inclusive. Each of those index values is regarded
+as a "brightness level" indicator. Thus from the user space perspective
+the range of available brightness levels is from 0 to 9 (max_brightness)
+inclusive.
+
+2 Notify user space about hotkey event
+
+There are generally two cases for hotkey event reporting:
+i) For some laptops, when user presses the hotkey, a scancode will be
+ generated and sent to user space through the input device created by
+ the keyboard driver as a key type input event, with proper remap, the
+ following key code will appear to user space:
+
+ EV_KEY, KEY_BRIGHTNESSUP
+ EV_KEY, KEY_BRIGHTNESSDOWN
+ etc.
+
+For this case, ACPI video driver does not need to do anything(actually,
+it doesn't even know this happened).
+
+ii) For some laptops, the press of the hotkey will not generate the
+ scancode, instead, firmware will notify the video device ACPI node
+ about the event. The event value is defined in the ACPI spec. ACPI
+ video driver will generate an key type input event according to the
+ notify value it received and send the event to user space through the
+ input device it created:
+
+ event keycode
+ 0x86 KEY_BRIGHTNESSUP
+ 0x87 KEY_BRIGHTNESSDOWN
+ etc.
+
+so this would lead to the same effect as case i) now.
+
+Once user space tool receives this event, it can modify the backlight
+level through the sysfs interface.
+
+3 Change backlight level in the kernel
+
+This works for machines covered by case ii) in Section 2. Once the driver
+received a notification, it will set the backlight level accordingly. This does
+not affect the sending of event to user space, they are always sent to user
+space regardless of whether or not the video module controls the backlight level
+directly. This behaviour can be controlled through the brightness_switch_enabled
+module parameter as documented in kernel-parameters.txt. It is recommended to
+disable this behaviour once a GUI environment starts up and wants to have full
+control of the backlight level.
diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index 9f401350f502..67f733d6f848 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -370,8 +370,10 @@ A: There is no clear spec defined way from ACPI that can give us that
CPUs in MADT as hotpluggable CPUS. In the case there are no disabled CPUS
we assume 1/2 the number of CPUs currently present can be hotplugged.
- Caveat: Today's ACPI MADT can only provide 256 entries since the apicid field
- in MADT is only 8 bits.
+ Caveat: ACPI MADT can only provide 256 entries in systems with only ACPI 2.0c
+ or earlier ACPI version supported, because the apicid field in MADT is only
+ 8 bits. From ACPI 3.0, this limitation was removed since the apicid field
+ was extended to 32 bits with x2APIC introduced.
User Space Notification
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 2fe6e767b3d6..7f64e0f0258a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3229,6 +3229,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
video= [FB] Frame buffer configuration
See Documentation/fb/modedb.txt.
+ video.brightness_switch_enabled= [0,1]
+ If set to 1, on receiving an ACPI notify event
+ generated by hotkey, video driver will adjust brightness
+ level and then send out the event to user space through
+ the allocated input device; If set to 0, video driver
+ will only send out the event without touching backlight
+ brightness level.
+ default: 1
+
virtio_mmio.device=
[VMMIO] Memory mapped virtio (platform) device.
diff --git a/Documentation/power/video_extension.txt b/Documentation/power/video_extension.txt
deleted file mode 100644
index b2f9b1598ac2..000000000000
--- a/Documentation/power/video_extension.txt
+++ /dev/null
@@ -1,37 +0,0 @@
-ACPI video extensions
-~~~~~~~~~~~~~~~~~~~~~
-
-This driver implement the ACPI Extensions For Display Adapters for
-integrated graphics devices on motherboard, as specified in ACPI 2.0
-Specification, Appendix B, allowing to perform some basic control like
-defining the video POST device, retrieving EDID information or to
-setup a video output, etc. Note that this is an ref. implementation
-only. It may or may not work for your integrated video device.
-
-Interfaces exposed to userland through /proc/acpi/video:
-
-VGA/info : display the supported video bus device capability like Video ROM, CRT/LCD/TV.
-VGA/ROM : Used to get a copy of the display devices' ROM data (up to 4k).
-VGA/POST_info : Used to determine what options are implemented.
-VGA/POST : Used to get/set POST device.
-VGA/DOS : Used to get/set ownership of output switching:
- Please refer ACPI spec B.4.1 _DOS
-VGA/CRT : CRT output
-VGA/LCD : LCD output
-VGA/TVO : TV output
-VGA/*/brightness : Used to get/set brightness of output device
-
-Notify event through /proc/acpi/event:
-
-#define ACPI_VIDEO_NOTIFY_SWITCH 0x80
-#define ACPI_VIDEO_NOTIFY_PROBE 0x81
-#define ACPI_VIDEO_NOTIFY_CYCLE 0x82
-#define ACPI_VIDEO_NOTIFY_NEXT_OUTPUT 0x83
-#define ACPI_VIDEO_NOTIFY_PREV_OUTPUT 0x84
-
-#define ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS 0x82
-#define ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS 0x83
-#define ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS 0x84
-#define ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS 0x85
-#define ACPI_VIDEO_NOTIFY_DISPLAY_OFF 0x86
-