[ltp] Some Fn special keys not working

[Adam Sloboda]

Hello,

I've come across Thinkpad keyboard issue.  I have older Thinkpad USB
keyboard (17ef:6009) and it suddenly stopped processing some Fn
combinations.  I think it started a while back around the time I
upgraded kernel from 4.19 to 5.5, I've been looking at changes to
hid-lenovo and thinkpad-acpi and didn't see anything suspicious.

Since that day Fn-F2 sleep key wasn't triggering suspend.

acpi_listen gives no event, evtest gives no event.  I tried to change
hotkey mask in thinkpad-acpi to "all" mask but it didn't work.  On old
thinkpad with old kernel I get this:

- ThinkVantage - triggers ACPI event and evtest event
- Fn-F2 - triggers ACPI event and evtest event
- Fn-F3 - triggers ACPI event and evtest event
- Fn-F9 - triggers evtest event

My old thinkpad has really old kernel (4.19.67-2+deb10u2 (2019-11-11))
and very similar keyboard as this USB keyboard and it still works there.
On a non-thinkpad machine with updated kernel (4.19.171-2 (2021-01-30))
I only get Fn-F9 event in evtest. On another laptop with Windows 10
Fn-F2 combination is locking screen.

My only clue is that thinkpad-acpi hotkey mask on this machine ends in
0xB and it may or may not have somthing to do with it at least as far as
ACPI event propagation goes. It's clearly not a hardware issue though.

Thanks for any pointers.

Regards,
Adam