faft: Refactoring soft reset test

Moved the states_list to be part of the plankton PD device class
similar to the changes for the hard_reset() method. In addition
added try/except clauses to method calls in the soft_reset test
script.

BRANCH=none
BUG=chrome-os-partner:50178
TEST=Manual
Tested with Samus to Plankton. Verfied that soft resets are initiated
and the state transition history can be used to verify expected operation.

Change-Id: I131f6b2784c77cfdb69210250d3dd5c11fd739c9
Signed-off-by: Scott <scollyer@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/340248
Commit-Ready: Scott Collyer <scollyer@chromium.org>
Tested-by: Scott Collyer <scollyer@chromium.org>
Reviewed-by: Todd Broch <tbroch@chromium.org>
diff --git a/server/cros/servo/pd_device.py b/server/cros/servo/pd_device.py
index 7f9d5c9..0d0d51a 100644
--- a/server/cros/servo/pd_device.py
+++ b/server/cros/servo/pd_device.py
@@ -91,10 +91,9 @@
         raise NotImplementedError(
                 'vbus_request should be implemented in derived class')
 
-    def soft_reset(self, states_list=None):
+    def soft_reset(self):
         """Initates a PD soft reset sequence
 
-        @param states_list: list of expected PD state transitions
         """
         raise NotImplementedError(
                 'soft_reset should be implemented in derived class')
@@ -277,7 +276,7 @@
             val = 'off'
         return bool(val == m[0][1])
 
-    def soft_reset(self, states_list=None):
+    def soft_reset(self):
         """Initates a PD soft reset sequence
 
         To verify that a soft reset sequence was initiated, the
@@ -285,8 +284,6 @@
         was acknowledged by its port pair. The connect state should
         be same as it was prior to issuing the reset command.
 
-        @param states_list: list of expected PD state transitions
-
         @returns True if the port pair acknowledges the the reset message
         and if following the command, the device returns to the same
         connected state. False otherwise.
@@ -480,13 +477,36 @@
         m = self.utils.send_pd_command_get_output(cmd, reply_exp)
         return self._verify_state_sequence(states_list, m[0][0])
 
-    def soft_reset(self, states_list):
+    def soft_reset(self):
         """Initates a PD soft reset sequence
 
-        @param states_list: list of expected PD state transitions
-
         @returns True if state transitions match, False otherwise
         """
+        snk_reset_states = [
+            'SOFT_RESET',
+            'SNK_DISCOVERY',
+            'SNK_REQUESTED',
+            'SNK_TRANSITION',
+            'SNK_READY'
+        ]
+
+        src_reset_states = [
+            'SOFT_RESET',
+            'SRC_DISCOVERY',
+            'SRC_NEGOCIATE',
+            'SRC_ACCEPTED',
+            'SRC_POWERED',
+            'SRC_TRANSITION',
+            'SRC_READY'
+        ]
+
+        if self.is_src():
+            states_list = src_reset_states
+        elif self.is_snk():
+            states_list = snk_reset_states
+        else:
+            raise error.TestFail('Port Pair not in a connected state')
+
         cmd = 'pd %d soft' % self.port
         return self._reset(cmd, states_list)