USB synaptics touchpad

Stefan Monnier monnier at iro.umontreal.ca
Thu Feb 7 09:02:52 PST 2008


>> I wonder how this is *supposed* to work (now or ideally in the future):
>> - is a synaptics-usb driver the right way to go, or should the Xorg driver
>> natively support synaptics-over-USB?
>> - how is the hotplug supposed to work?  Is it a missing feature in the
>> Xorg-synaptics driver, or a bug in the synaptics-usb driver?

> I don't know much about hotplug in X, but probably the first thing to look
> at is whether the kernel knows about the touchpad.  I.e., if you type the
> command "cat /sys/class/input/event*/device/name", is there a line mentioning
> Synaptics in it?  Try that test with and without the synaptics-usb driver,
> and try it after suspend/resume.

Actually, I got it to work now.  The trick is to make sure that the
touchpad gets the same device name after unplug&replug.  I do that in
2 steps:

1 - use a udev rule so that the touchpad is always available as
    /dev/input/touchpad:

    kernel=="event*", DRIVERS=="synaptics-usb", SYMLINK+="input/touchpad"

2 - Force the synaptics driver to use that special device name:

        Option          "Device"        "/dev/input/touchpad"
        Option          "Protocol"      "event"

And now after I unplug&replug the keyboard&touchpad, all I have to do is
switch console so as to force the synaptics driver to close and re-open
the device.


        Stefan




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