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linux-next/Documentation/laptops/lg-laptop.rst
Matan Ziv-Av dbf0c5a6b1 platform/x86: Add LG Gram laptop special features driver
A driver for LG Gram laptop supporting features not available through the
standard interfaces:

- Support for the 5 Fn keys that generate ACPI or WMI events.

- Two software controlled LEDs: keyboard backlight (also controlled by
  hardware) and touchpad LED.

- Extra features: reader mode, Fn lock, cooling mode, USB charge mode, and
  maximal battery charging level.

Signed-off-by: Matan Ziv-Av <matan@svgalib.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2018-10-19 19:21:57 +03:00

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.. SPDX-License-Identifier: GPL-2.0+
LG Gram laptop extra features
=============================
By Matan Ziv-Av <matan@svgalib.org>
Hotkeys
-------
The following FN keys are ignored by the kernel without this driver:
- FN-F1 (LG control panel) - Generates F15
- FN-F5 (Touchpad toggle) - Generates F13
- FN-F6 (Airplane mode) - Generates RFKILL
- FN-F8 (Keyboard backlight) - Generates F16.
This key also changes keyboard backlight mode.
- FN-F9 (Reader mode) - Generates F14
The rest of the FN key work without a need for a special driver.
Reader mode
-----------
Writing 0/1 to /sys/devices/platform/lg-laptop/reader_mode disables/enables
reader mode. In this mode the screen colors change (blue color reduced),
and the reader mode indicator LED (on F9 key) turns on.
FN Lock
-------
Writing 0/1 to /sys/devices/platform/lg-laptop/fn_lock disables/enables
FN lock.
Battery care limit
------------------
Writing 80/100 to /sys/devices/platform/lg-laptop/battery_care_limit
sets the maximum capacity to charge the battery. Limiting the charge
reduces battery capacity loss over time.
This value is reset to 100 when the kernel boots.
Fan mode
--------
Writing 1/0 to /sys/devices/platform/lg-laptop/fan_mode disables/enables
the fan silent mode.
USB charge
----------
Writing 0/1 to /sys/devices/platform/lg-laptop/usb_charge disables/enables
charging another device from the USB port while the device is turned off.
This value is reset to 0 when the kernel boots.
LEDs
~~~~
The are two LED devices supported by the driver:
Keyboard backlight
------------------
A led device named kbd_led controls the keyboard backlight. There are three
lighting level: off (0), low (127) and high (255).
The keyboard backlight is also controlled by the key combination FN-F8
which cycles through those levels.
Touchpad indicator LED
----------------------
On the F5 key. Controlled by led device names tpad_led.