LG Gram laptop extra features — The Linux Kernel 5.18.5-gnu-1 documentation

# 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 F21

- FN-F6 (Airplane mode) - Generates RFKILL

- FN-F9 (Reader mode) - Generates F14

The rest of the FN keys 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/class/power_supply/CMB0/charge_control_end_threshold 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.