The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/atrusctl/+/6b432ca5f692d457b91052acd83ec4be453423cf

commit 6b432ca5f692d457b91052acd83ec4be453423cf
Author: Emil Lundmark <lndmrk@chromium.org>
Date: Thu Jul 06 12:00:30 2017

Ignore additional connected devices

We only need to support the use case where a single Atrus device is
connected to a CfM. This change will ensure that additional devices that
are connected will be ignored and don't e.g. clobber the logs.

BUG= chromium:737502 
TEST=Connected two devices and verified that the second one was ignored

Change-Id: Ia311ee033bfac4bb853d456fc169156128d9da54
Reviewed-on: https://chromium-review.googlesource.com/552152
Commit-Ready: Emil Lundmark <lndmrk@chromium.org>
Tested-by: Emil Lundmark <lndmrk@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Karl Petersson <karl@limesaudio.com>

[modify] https://crrev.com/6b432ca5f692d457b91052acd83ec4be453423cf/src/atrusd.cc

lndmrk@ - the bug summary and the CL description seem to be contradicting. My understanding is that multiple Atrus devices should be allowed. Please confirm.

Thanks

harpreet@ for now, only a single device is supported (via USB). The CL
fixes an issue when you connect multiple devices, it essentially ignores
the additional devices.

lndmrk@ - to be clear about what "ignored" means, if there are multiple atrus' connected to guado via USB, only 1 of them will be functional? Others will essentially act as if they are not even powered on?

They will all be functional and powered on, but atrusctl will only
talk with one of them (the first one) and ignore the rest.