I am reporting this here as I don't know if this belongs here or to the kernel
bugzilla.

On openSUSE Tumbleweed the "fn" button does not work at all. On Windows, after
installing a driver from the Lenovo website [1], it works.

[1]: https://datacentersupport.lenovo.com/it/it/accessories/acc500323

---
$ lsusb

...
Bus 004 Device 002: ID 1a81:1026 Holtek Semiconductor, Inc. Lenovo Essential
Wireless Combo Keyboard & Mouse Gen2

---
# evtest

Available devices:
/dev/input/event0:      AT Translated Set 2 keyboard
/dev/input/event1:      ETPS/2 Elantech TrackPoint
/dev/input/event10:     Sleep Button
/dev/input/event11:     ThinkPad Extra Buttons
/dev/input/event12:     PC Speaker
/dev/input/event13:     HD-Audio Generic HDMI/DP,pcm=3
/dev/input/event14:     HD-Audio Generic HDMI/DP,pcm=7
/dev/input/event15:     HD-Audio Generic HDMI/DP,pcm=8
/dev/input/event16:     HDA Digital PCBeep
/dev/input/event17:     HD-Audio Generic Mic
/dev/input/event18:     HD-Audio Generic Headphone
/dev/input/event2:      ETPS/2 Elantech Touchpad
/dev/input/event3:      Video Bus
/dev/input/event4:      Lenovo Lenovo Essential Wireless Combo Keyboard & Mouse
Gen2
/dev/input/event5:      Lenovo Lenovo Essential Wireless Combo Keyboard & Mouse
Gen2 Mouse
/dev/input/event6:      Lenovo Lenovo Essential Wireless Combo Keyboard & Mouse
Gen2 Consumer Control
/dev/input/event7:      Lenovo Lenovo Essential Wireless Combo Keyboard & Mouse
Gen2
/dev/input/event8:      Power Button
/dev/input/event9:      Lid Switch
---

I've tried running evtest, but nothing gets detected when pressing the fn
button alone, and the normal F1-F12 are detected if pressed while holding fn.
Same with xev.

If I run evtest and select event6, i get _some_ fn keys displayed (some keys
are right and some are wrong) but they are not detected:

---
Select the device event number [0-18]: 6
Input driver version is 1.0.1
Input device ID: bus 0x3 vendor 0x1a81 product 0x1026 version 0x1001
Input device name: "Lenovo Lenovo Essential Wireless Combo Keyboard & Mouse
Gen2 Consumer Control"
Supported events:
  Event type 0 (EV_SYN)
  Event type 1 (EV_KEY)
    Event code 113 (KEY_MUTE)                 # <- this is right
    Event code 114 (KEY_VOLUMEDOWN)           # <- right
    Event code 115 (KEY_VOLUMEUP)             # <- right
    Event code 140 (KEY_CALC)                 # <- wrong. should be mic mute
    Event code 155 (KEY_MAIL)                 # <- from here on, all wrong
    Event code 163 (KEY_NEXTSONG)
    Event code 164 (KEY_PLAYPAUSE)
    Event code 165 (KEY_PREVIOUSSONG)
    Event code 166 (KEY_STOPCD)
    Event code 172 (KEY_HOMEPAGE)
    Event code 217 (KEY_SEARCH)
    Event code 240 (KEY_UNKNOWN)
  Event type 4 (EV_MSC)
    Event code 4 (MSC_SCAN)
Properties:
Testing ... (interrupt to exit)
---

System infos:

$ cat /etc/os-release -p

NAME="openSUSE Tumbleweed"
# VERSION="20240403"
ID="opensuse-tumbleweed"
ID_LIKE="opensuse suse"
VERSION_ID="20240403"
PRETTY_NAME="openSUSE Tumbleweed"
ANSI_COLOR="0;32"
# CPE 2.3 format, boo#1217921
CPE_NAME="cpe:2.3:o:opensuse:tumbleweed:20240403:*:*:*:*:*:*:*"
#CPE 2.2 format
#CPE_NAME="cpe:/o:opensuse:tumbleweed:20240403"
BUG_REPORT_URL="https://bugzilla.opensuse.org"
SUPPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org"
DOCUMENTATION_URL="https://en.opensuse.org/Portal:Tumbleweed"
LOGO="distributor-logo-Tumbleweed"