plankton: allow use of double CC cable

Add ability for Plankton to detect whether a single or double
CC cable is used to connect to DUT. This is done by toggling
the active CC line until a connection is detected, then toggling
once more and checking if we still have a connection. If we
can connect to the DUT in both CC polarities, then it is a
double CC cable. Before we know the cable type, keep PD
communication disabled to avoid partially negotiating and then
disconnecting. Note, this increases the time it takes for
us to connect a form a stable PD contract with the DUT.

When we detect a double CC cable, the cable flip button actually
flips the active CC polarity, thus testing all pins in the
opposite polarity.

BUG=chrome-os-partner:42569
BRANCH=smaug
TEST=test with plankton and samus. test that we form a PD
contract with both single and double CC cables as both sink
and source. also test the cable flip button for both cables.

Change-Id: I522369302848d4cdbb70c55a40af3ad0b7c3fb8a
Signed-off-by: Alec Berg <alecaberg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/286589
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

0 files changed, 0 insertions, 0 deletions