How do I get the Lenovo "Fn Lock" light to work under Ubuntu?

I have a Lenovo E595 running Ubuntu 20.04. The "Fn Lock" feature on the keyboard works in terms of how it modifies presses of the F1-F12 keys, but the little light on the Esc key doesn't show the current state.

To be clear:

• I press F5 a few times, and the screen brighness is adjusted.
• I press Fn+Esc, and "Fn Lock" is now on, but the light hasn't changed.
• I press F5 again, or several times, and it acts as a normal F5 (ie my browser might refresh the page).
• I press Fn+Esc again, and "Fn Lock" is now off, but again the light hasn't changed.

So, "Fn Lock" works in the sense that it modifies what keypresses do, but the little light on the Esc key doesn't come on. Under Windows the light does toggle, to show the current status.

The behaviour is the same on Xorg and Wayland.

Does anyone know how to get the "Fn Lock" light to work under Ubuntu?

2 Answers

I just found the "problem" Pressing Fn+Esc doesn't turn on/off the Fnlock light anymore. I had to go to Lenovo Vantage software: "Input & Accessories" , "Keyboard". then there a could change de light status to on/off...

A code fix has recently been found, but has not yet been upstreamed at the time I write this. Details are on the kernel bugzilla and ubuntu launchpad reports: