Lenovo IdeaPad 720s (Ryzen)
The Lenovo IdeaPad 720s (Ryzen) is a laptop computer with a 13.3" screen, AMD Ryzen™ processor, webcam, microphone, audio in/out, 80211ac wireless card with bluetooth 4.1, 1 USB 3.0 Type-C (DP & Power Delivery), 1 x USB 3.0 Type-C (DP), 2 USB3 ports, and a fingerprint reader.
CPU/APU-wise, Linux support for the 720s is in decent shape since kernel ~4.15 (CPU and GPU temperatures per lm_sensors); the more recent the better. Its rtl8821ce WLAN and Bluetooth chip has no mainlined driver (as of 4.17), but rtl8821ce-dkms-gitAUR comes to rescue here.
UEFI
Before installing, disable Secure Boot in the BIOS. You can access the BIOS by pressing F2 at the Splash screen. The boot menu can also be accessed by pressing F12.
Video
X works natively with a current linux and xf86-video-amdgpu.
If you are having video issues with only the xf86-video-amdgpu installed, also install the AMD PRO package amdgpu-pro-libglAUR. See AMDGPU
Sound
Sound works with PulseAudio in linux 4.15-1 from testing repository.
Webcam
Chicony EasyCamera (USB)
Works out of the box on linux 4.19.12.
Wireless
The rtl8821ce-dkms-gitAUR wireless driver is required in order for WiFi and Bluetooth to work.
Sometimes upon reboot, rfkill may block wireless communications. To unblock, run : rfkill unblock all.
Active bluetooth may lock up the PC on lid close/suspend, then rfkill block bluetooth.
Touchpad
Works out of the box with mutli-finger scrolling on linux 4.15-1 in X.
Function keys
No dedicated keys. The Fn functions on the F{1..12} keys are correctly recognised by X11 and work out of the box (Touchpad on/off etc.). Fn state can be inverted in the BIOS menu.
ACPI annoyances
ttys get filled with massive amounts of ACPI complaints, and are unusable as such. Mitigate by passing the pci=noaer kernel commandline option.
CPU soft lockup
The mwait cpu instruction can cause a CPU soft lockup.
To fix the issue, add idle=nomwait to kernel parameters.