USB Lenovo ThinkPad Compact Keyboard has fn_lock inverted

I have an external ThinkPad USB keyboard:

$ lsusb | grep -i keyboard
Bus 003 Device 022: ID 17ef:6047 Lenovo ThinkPad Compact Keyboard with TrackPoint

The Linux kernel exposes a fn_lock attribute in sysfs for this keyboard:

$ cat
sys/devices/pci0000:00/0000:00:14.0/usb3/3-5/3-5.4/3-5.4.3/3-5.4.3:1.1/0003:17EF:6047.000F/fn_lock
1

However, this attribute appears inverted for this particular keyboard:
it seems to be 1 when FnLock is *disabled* and 0 when FnLock is *enabled*. In order to enable FnLock, I have to write 0 to this file.

(Also, separately from that, it would be nice if the kernel could handle fn_lock toggling *internally*, rather than expecting userspace to do it. As far as I can tell, it does handle similar things for some keyboards, but not this one.)

Under Windows the default actions of the Function keys are the media keys, i.e. pressing F1 is Mute. Fn-"Mute" is F1, or enabling Fn-Lock & "Mute". That's why when /fn_lock is 1, the Mute key is F1.

With keyboards built into Thinkpads there's a BIOS setting to invert the behaviour of Fn-Lock (and thus have Fn keys by default), as well as swapping Fn<->Ctrl, but there's no equivalent option for the external keyboards.

What's the wrong way around here is hid-lenovo assumes that you want Fn-Lock on when connecting to the keyboard, not off. My assumption at the time was that whilst it's different to how the keyboard behaves under Windows, it'd be a more useful default.

Agreed. This was something I looked into when I was adding support for the keyboards. For yours it's a pretty trivial addition, but for the USB variant you can't send the command in the middle of the USB interrupt receiving the keypress, solving this seemed to require quite a lot of boilerplate for what would have been pretty trivial in userland.

Of course, It's very easily possible that I missed something, or there's a helper to do this sort of thing that now exists.

Cheers,