lgctl: fan, battery charge limit, power profile and speakers for LG Gram laptops on Linux

lgctl gives Linux users of LG Gram laptops the controls that LG only ships in its Windows app: fan mode (silent / normal / boost), the battery charge limit (stop at 80 %), and the system power profile, plus live temperatures, CPU frequency and power. On the 2023 Gram Style it also brings the internal speakers to life (see below). It comes as a command-line tool (lgctl) and a small desktop window (lgctl-gui, "LG Control" in your application menu, with a tray icon).

Developed and tested on an LG Gram 16Z90RS (Intel Core i7-1360P) running Fedora 44 with the COSMIC desktop. It should work on any LG Gram supported by the kernel's lg_laptop driver and on any desktop (GNOME, KDE Plasma, COSMIC, Sway...), as long as power profiles are provided by power-profiles-daemon or tuned-ppd.

What it does, and how

Everything goes through standard kernel interfaces, no daemon (the speaker fix is a one-shot systemd unit):

Setting / reading	Where it lives
Fan mode (0/1/2)	/sys/devices/platform/lg-laptop/fan_mode (kernel lg_laptop)
Charge limit (80/100)	/sys/class/power_supply/BAT0/charge_control_end_threshold
Power profile	net.hadess.PowerProfiles on the system D-Bus (ppd / tuned-ppd)
Battery level, health	/sys/class/power_supply/BAT0/* (energy_full vs. design, cycles)
CPU temperatures	hwmon coretemp
CPU frequency	cpufreq scaling_cur_freq
CPU package power	RAPL intel-rapl:0/energy_uj, sampled once per second
GPU frequency	i915 gt/gt0/rps_act_freq_mhz
NVMe, chassis	hwmon nvme, acpitz
Speaker amplifiers	HDA codec hwdep /dev/snd/hwC0D0 (root), see below

The fan and charge settings are stored by the LG firmware, so they survive a reboot. The firmware reports no real fan speed (its ACPI value is a constant), so none is shown. Changing the power profile goes through the daemon, so the desktop's own selector stays in sync.

Speakers on the LG Gram Style (16Z90RS)

The 2023 Gram Style has a Realtek ALC298 codec with the speakers behind I2C amplifiers that must be programmed before they make a sound. The kernel does this only for models in its quirk table: the 14-inch (1854:0490) is there since Linux 7.0 (ALC298_FIXUP_LG_GRAM_STYLE_14), the 16-inch (1854:0492) is not yet, so its speakers are silent under Linux while headphones and HDMI work. A one-line kernel patch adding the 16-inch ID is being submitted; until it reaches your distribution, lgctl replays the kernel's own sequence from userspace:

lgctl speakers              status: codec, last apply, service state
sudo lgctl speakers apply   initialise and enable the amplifiers
lgctl speakers start        same, through the systemd unit (polkit, no sudo)

lgctl-speakers.service runs the apply at boot and after resume. The RPM enables it automatically on a 16Z90RS; from source, sudo make install-system does. The GUI and its tray menu show when the fix was last applied and offer "Apply now"; the polkit rule in packaging/50-lgctl.rules lets members of wheel do that without a password.

The tray menu also switches the power profile and the fan mode. The "Startup" card of the window decides whether LG Control starts at login and whether it starts in the tray only or with its window; the choice is written to ~/.config/autostart/lgctl-tray.desktop, which overrides the system entry.

Writing to the codec's hwdep device requires CAP_SYS_RAWIO, which is why this one command needs root. "Applied" means the sequence ran since boot: the amplifiers cannot be read back. Only the two amplifiers the 16-inch actually has (0x38, 0x39) are programmed by default; --amps all also drives the 0x3c/0x3d pair of the 14-inch. lgctl speakers refuses to run on a codec it does not recognise unless given --force.

Usage

lgctl                                   status
lgctl fan silent|normal|boost           fan mode
lgctl charge 80|100                     charge limit
lgctl profile battery|balanced|performance
lgctl watch [seconds]                   live view, Ctrl-C to quit
lgctl speakers [apply|on|off|start]     speaker amplifiers (Gram Style)
lgctl setup                             how to run without sudo
lgctl version
lgctl-gui                               the window ("LG Control" in the menu)
lgctl-gui --tray                        start hidden in the tray (autostart entry)

Example status:

profile   balanced
fan       normal (0)
battery   100% not charging on AC, limit 80%
health    101%  80.7 / 80.0 Wh design, 4 cycles
cpu       56 °C package  cores 50 52 54 54 54 54 55 55 55 55 50 50
cpu freq  853 MHz avg, 1466 MHz max
cpu power 4.6 W  (PL1 28 W)
gpu       idle
nvme      45 °C   chassis 32 °C

Install

RPM (Fedora and derivatives)

Grab the RPM from the releases page, then:

sudo dnf install ./lgctl-*.rpm

The package installs both binaries, the menu entry, the tray autostart entry, the icon, the udev and polkit rules and the speaker unit, and reloads udev, so everything works right away for members of the wheel group. Remove the autostart entry (/etc/xdg/autostart/lgctl-tray.desktop) if you do not want the tray icon at login.

From source

sudo dnf install golang gcc mesa-libGL-devel libXcursor-devel libXrandr-devel \
    libXinerama-devel libXi-devel libXxf86vm-devel libxkbcommon-devel wayland-devel
make                # builds lgctl and lgctl-gui
make install-user   # binaries, menu and autostart entries, icon under ~/.local (no root)
sudo make install-system   # /usr/bin/lgctl, udev + polkit rules, speaker unit (enabled)
make rpm            # builds the RPM (needs rpm-build rpmdevtools systemd-rpm-macros)

Running without sudo

The fan mode, the charge limit and the CPU energy counter are root-only by default. lgctl setup prints three udev rules that hand them to the wheel group, which is what the RPM installs. By hand:

lgctl setup --rules | sudo tee /etc/udev/rules.d/90-lgctl.rules > /dev/null
sudo udevadm control --reload
sudo udevadm trigger /sys/devices/platform/lg-laptop /sys/class/power_supply/BAT0 /sys/class/powercap/intel-rapl:0

The power profile never needs root: the daemon's policy allows the active session to change it.

Requirements

• An LG Gram with the lg_laptop kernel module loaded (automatic on supported models; ls /sys/devices/platform/lg-laptop should list fan_mode).
• power-profiles-daemon or tuned-ppd for the power profile.
• An Intel CPU for the RAPL power reading (other readings degrade gracefully).

Tips for Intel iGPU laptops

Two things learned while building this, both relevant to gaming on an LG Gram:

• The Performance profile shipped by tuned (throughput-performance) is a server profile: it pins the CPU at its maximum frequency, which steals power budget from the integrated GPU. Games run better in Balanced. A laptop friendly Performance profile is simply include=balanced plus energy_performance_preference=performance.
• The Battery profile disables turbo entirely. include=powersave plus boost=1 keeps the machine usable on battery.

See /usr/lib/tuned/profiles/ for the shipped profiles and /etc/tuned/ppd.conf to map your own onto the desktop's three modes.

License

MIT. Contributions and reports from other LG Gram models are welcome.