Clickpads with a fake right button
libinput relies on the kernel to label Clickpads
with the INPUT_PROP_BUTTONPAD property so it can enable the correct
Clickpad software button behavior. Clickpads are not expected to have a right button
since the whole surface can be depressed.
A common bug encountered with Clickpads is that the device advertises a physical right button where no such button exists. This is usually a bug in the firmware of the device and causes the following warning to be emitted by libinput:
"<device name> clickpad advertising right button"
The user-visible effect of this is usually negligible since these devices cannot actually trigger a right click and libinput’s default behaviors for clickpads work as expected.
However, we should nonetheless correct the device to get rid of this warning and avoid potential issues with future features. The Device quirks provide a simple way to disable the fake right button on the device. The following quirk disables the right button on the MyModel laptop from the MyVendor OEM:
[MyVendor MyModel Touchpad]
MatchName=Foo Bar Touchpad
MatchUdevtype=touchpad
MatchDMIModAlias=dmi:*svnMyVendor:pnMyModel:*
AttrEventCode=-BTN_RIGHT
The name of the device can be obtained using libinput record,
the modalias match is a shell-style glob against the value of /sys/class/dmi/id/modalias.
In most cases, matching should be against svn (system vendor) and one of
pn (product name) or pvr (product version), whichever provides a
useful description of the individual laptop model. See the
Device quirks documentation for details on testing local quirks.
For reference, some example commits that add such a quirk are: