Touchpad LED not working on some Dell Vostro

[James M. Leddy]

Tracking bug to ensure that this fix makes it in to ubuntu

Fixed by this commit:

commit 2d8b90be4f1cadd9921312e2983459f568d29cd1
Author: AceLan Kao <email address hidden>
Date: Tue Oct 4 16:25:44 2011 +0800

    dell-laptop: support Synaptics/Alps touchpad led

    This patch supports Dell laptop with Synaptics and Alps touchpad chip
    that with LED to indicate the functionality of touchpad is disabled or
    enabled.

    The command for touchpad LED is 0x97, and the data 1 means turn on the
    touchpad LED, 2 means turn it off.

    BTW, I add dell_quirks to white list those machines that supports this
    behavior, so that the code won't affect those who don't have a touchpad LED
    machine.

    We can easily to turn it on/off by
       echo 1 > /sys/class/leds/dell-laptop::touchpad/brightness
       echo 0 > /sys/class/leds/dell-laptop::touchpad/brightness

    Signed-off-by: AceLan Kao <email address hidden>
    Signed-off-by: Matthew Garrett <email address hidden>