path: root/Documentation/thinkpad-acpi.txt
diff options
Diffstat (limited to 'Documentation/thinkpad-acpi.txt')
1 files changed, 77 insertions, 19 deletions
diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index eb2f5986e1eb..60953d6c919d 100644
--- a/Documentation/thinkpad-acpi.txt
+++ b/Documentation/thinkpad-acpi.txt
@@ -1,7 +1,7 @@
ThinkPad ACPI Extras Driver
- Version 0.15
- July 1st, 2007
+ Version 0.16
+ August 2nd, 2007
Borislav Deianov <borislav@users.sf.net>
Henrique de Moraes Holschuh <hmh@hmh.eng.br>
@@ -161,20 +161,22 @@ system. Enabling the hotkey functionality of thinkpad-acpi signals the
firmware that such a driver is present, and modifies how the ThinkPad
firmware will behave in many situations.
+The driver enables the hot key feature automatically when loaded. The
+feature can later be disabled and enabled back at runtime. The driver
+will also restore the hot key feature to its previous state and mask
+when it is unloaded.
When the hotkey feature is enabled and the hot key mask is set (see
-below), the various hot keys either generate ACPI events in the
-following format:
+below), the driver will report HKEY events in the following format:
ibm/hotkey HKEY 00000080 0000xxxx
-or events over the input layer. The input layer support accepts the
-standard IOCTLs to remap the keycodes assigned to each hotkey.
+Some of these events refer to hot key presses, but not all.
-When the input device is open, the driver will suppress any ACPI hot key
-events that get translated into a meaningful input layer event, in order
-to avoid sending duplicate events to userspace. Hot keys that are
-mapped to KEY_RESERVED in the keymap are not translated, and will always
-generate an ACPI ibm/hotkey HKEY event, and no input layer events.
+The driver will generate events over the input layer for hot keys and
+radio switches, and over the ACPI netlink layer for other events. The
+input layer support accepts the standard IOCTLs to remap the keycodes
+assigned to each hot key.
The hot key bit mask allows some control over which hot keys generate
events. If a key is "masked" (bit set to 0 in the mask), the firmware
@@ -256,6 +258,20 @@ sysfs notes:
disabled" postition, and 1 if the switch is in the
"radios enabled" position.
+ hotkey_report_mode:
+ Returns the state of the procfs ACPI event report mode
+ filter for hot keys. If it is set to 1 (the default),
+ all hot key presses are reported both through the input
+ layer and also as ACPI events through procfs (but not
+ through netlink). If it is set to 2, hot key presses
+ are reported only through the input layer.
+ This attribute is read-only in kernels 2.6.23 or later,
+ and read-write on earlier kernels.
+ May return -EPERM (write access locked out by module
+ parameter) or -EACCES (read-only).
input layer notes:
A Hot key is mapped to a single input layer EV_KEY event, possibly
@@ -393,21 +409,63 @@ unknown by the driver if the ThinkPad firmware triggered these events on
hot key press or release, but the firmware will do it for either one, not
-If a key is mapped to KEY_RESERVED, it generates no input events at all,
-and it may generate a legacy thinkpad-acpi ACPI hotkey event.
+If a key is mapped to KEY_RESERVED, it generates no input events at all.
If a key is mapped to KEY_UNKNOWN, it generates an input event that
-includes an scan code, and it may also generate a legacy thinkpad-acpi
-ACPI hotkey event.
-If a key is mapped to anything else, it will only generate legacy
-thinkpad-acpi ACPI hotkey events if nobody has opened the input device.
+includes an scan code. If a key is mapped to anything else, it will
+generate input device EV_KEY events.
Non hot-key ACPI HKEY event map:
0x5001 Lid closed
0x5002 Lid opened
0x7000 Radio Switch may have changed state
+The above events are not propagated by the driver, except for legacy
+compatibility purposes when hotkey_report_mode is set to 1.
+Compatibility notes:
+ibm-acpi and thinkpad-acpi 0.15 (mainline kernels before 2.6.23) never
+supported the input layer, and sent events over the procfs ACPI event
+To avoid sending duplicate events over the input layer and the ACPI
+event interface, thinkpad-acpi 0.16 implements a module parameter
+(hotkey_report_mode), and also a sysfs device attribute with the same
+Make no mistake here: userspace is expected to switch to using the input
+layer interface of thinkpad-acpi, together with the ACPI netlink event
+interface in kernels 2.6.23 and later, or with the ACPI procfs event
+interface in kernels 2.6.22 and earlier.
+If no hotkey_report_mode module parameter is specified (or it is set to
+zero), the driver defaults to mode 1 (see below), and on kernels 2.6.22
+and earlier, also allows one to change the hotkey_report_mode through
+sysfs. In kernels 2.6.23 and later, where the netlink ACPI event
+interface is available, hotkey_report_mode cannot be changed through
+sysfs (it is read-only).
+If the hotkey_report_mode module parameter is set to 1 or 2, it cannot
+be changed later through sysfs (any writes will return -EPERM to signal
+that hotkey_report_mode was locked. On 2.6.23 and later, where
+hotkey_report_mode cannot be changed at all, writes will return -EACES).
+hotkey_report_mode set to 1 makes the driver export through the procfs
+ACPI event interface all hot key presses (which are *also* sent to the
+input layer). This is a legacy compatibility behaviour, and it is also
+the default mode of operation for the driver.
+hotkey_report_mode set to 2 makes the driver filter out the hot key
+presses from the procfs ACPI event interface, so these events will only
+be sent through the input layer. Userspace that has been updated to use
+the thinkpad-acpi input layer interface should set hotkey_report_mode to
+Hot key press events are never sent to the ACPI netlink event interface.
+Really up-to-date userspace under kernel 2.6.23 and later is to use the
+netlink interface and the input layer interface, and don't bother at all
+with hotkey_report_mode.