On Tue, Jun 06, 2017 at 08:09:50PM +0200, Julian Exner wrote:

Hi all,

sorry for neglecting this thread for so long. And thanks Ulrik for pointing
me to the formalities.

quoted

I was kind of surprised at first that the value was 0x33 instead of 0x3
until I read the documentation pointers Julian provided.

It seems like some kind of softswitch or masking for the individual buttons.
One of the 4-bit nibbles indicates the number of available buttons in
hardware, the other one the number of activated buttons.

quoted

I really would like this patch to become part of the linux kernel and
I hope that Julian will go through the formalities for patch submission.

I'm willing to do so, but I'm very short on time currently. Additionally, I
checked on a Thinkpad forum and was told that there are Thinkpads from the
90s with two buttons (e.g. ThinkPad 760 and those before ThinkPad
390/600/770). So I'm a bit afraid that simply setting the default to three
buttons may break something for these models and a more elaborate patch may
be necessary.

how many of these do you expect to still be alive *and* in need of a new
kernel? wikipedia says the 760 was produced 1995 to 1998 which would make
the newest of them 19 years old now. I'd rather have a hwdb quirk for those
in userspace, because disabling event codes is trivial.

Cheers,
   Peter