[gentoo-user] Why did Synaptics touchpad stop working?

[Grant Edwards <grant.b.edwards@gmail.com>]

This morning when I booted my Thinkpad T580, the Synaptics touchpad
buttons didn't work at all, and the "pointer" function just barely
worked: the response was slow and jerky with a noticeable delay.

In order to get it working again, I had to enable some rmi4 stuff in
my kernel config:

    < # CONFIG_RMI4_CORE is not set
    ---
    > CONFIG_RMI4_CORE=y
    > # CONFIG_RMI4_I2C is not set
    > CONFIG_RMI4_SMB=m
    > CONFIG_RMI4_F03=y
    > CONFIG_RMI4_F03_SERIO=y
    > CONFIG_RMI4_2D_SENSOR=y
    > CONFIG_RMI4_F11=y
    > CONFIG_RMI4_F12=y
    > # CONFIG_RMI4_F30 is not set
    > # CONFIG_RMI4_F34 is not set
    > # CONFIG_RMI4_F3A is not set
    > # CONFIG_RMI4_F55 is not set

Apparently, it used to work as a PS/2 mouse, but then it "just quit",
and I hand to enable rmi4 SMBus support.  The Gentoo Wiki page didn't
mention the rmi4 options and instead said to enable some I2C HID stuff
that didn't seem to be relevent for my hardware.

There was a dmsg message that pointed me towards the rmi4 options.

What's really bugging me is why did it quit working?

Nothing relevent seems to have been updated recently:

    1725658908:  >>> emerge (1 of 6) dev-libs/libffi-3.4.6 to /
    1725658926:  >>> emerge (2 of 6) dev-libs/gobject-introspection-1.78.1-r1 to /
    1725658987:  >>> emerge (3 of 6) media-libs/graphene-1.10.8-r1 to /
    1725659006:  >>> emerge (4 of 6) gui-libs/gtk-4.12.5-r2 to /
    1725659219:  >>> emerge (5 of 6) app-crypt/gcr-4.2.1 to /
    1725659258:  >>> emerge (6 of 6) app-crypt/pinentry-1.3.0-r3 to /

    1725762247:  >>> emerge (1 of 7) sys-firmware/intel-microcode-20240813_p20240815 to /
    1725762261:  >>> emerge (2 of 7) dev-python/jaraco-context-6.0.1 to /
    1725762273:  >>> emerge (3 of 7) dev-python/setuptools-73.0.1 to /
    1725762292:  >>> emerge (4 of 7) dev-python/idna-3.8 to /
    1725762305:  >>> emerge (5 of 7) dev-python/truststore-0.9.2 to /
    1725762317:  >>> emerge (6 of 7) gui-libs/gtk-4.14.4-r1 to /
    1725762557:  >>> emerge (7 of 7) www-client/google-chrome-128.0.6613.119 to /

I did boot into Windows yesterday at one point, but I do that fairly
regularly (a few times a month) and it has never caused any problems
in the past.

As I said, I've got it working again, but I'm baffled what caused it
to stop working.

--
Grant