Alex, whom owns support for Sumo?

I'm not sure if I'm supposed to be the owner, but I've got a Sumo and am going to check out this issue shortly.  I suspect the driver is just not set up in kernel 4.4.  Sumo uses a different touchscreen than any of our other devices by a vendor called Weida.  No one on touch knew this device was going to be switched to a new kernel, so we were unable to make sure that it would work before

I'll figure out what's wrong

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/kernel/+/7b45798a8090a6a0203036a9df9bb538bc33609d

commit 7b45798a8090a6a0203036a9df9bb538bc33609d
Author: Charlie Mooney <charliemooney@chromium.org>
Date: Wed Feb 15 21:33:09 2017

CHROMIUM: config: Enable wdt87xx_i2c driver

This driver is used for Weida touchscreens like that used in Sumo.  As
Sumo has been moved to kernel 4.4, this driver must be compiled into the
4.4 kernel or the touchscreen will neither work nor update.  This CL
just adds the wdt87xx_i2c driver.

BUG= chromium:690661 
TEST=I rebuilt the kernel and deployed on my Sumo.  With the new kernel,
the driver was listed under /sys/bus/i2c/drivers, the touchscreen
worked, and the touch firmware updater saw the screen and the logs
were as expected.

Change-Id: I4b6f36367a08de9c0d7108779d385f0750e16034
Signed-off-by: Charlie Mooney <charliemooney@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/442095
Reviewed-by: Benson Leung <bleung@chromium.org>

[modify] https://crrev.com/7b45798a8090a6a0203036a9df9bb538bc33609d/chromeos/config/x86_64/common.config

Fixed in ToT -- When I tried out the latest-canary image on my Sumo this morning the touchscreen worked.

Machines in the lab are passing now too