mcu: Track stepqueues separately from steppers

The MCU() class needs to track the stepqueues so that it can
initialize the steppersync object.  Track the stepqueues directly
instead of via the list of steppers.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/mcu.py

@@ -48,7 +48,6 @@ class MCU_stepper:
             " min_stop_interval=TICKS(%.9f) invert_step=%d" % (
                 self._oid, self._step_pin, self._dir_pin,
                 min_stop_interval, self._invert_step))
-        self._mcu.register_stepper(self)
         step_cmd = self._mcu.lookup_command(
             "queue_step oid=%c interval=%u count=%hu add=%hi")
         dir_cmd = self._mcu.lookup_command(
@@ -63,6 +62,7 @@ class MCU_stepper:
             max_error, step_cmd.msgid, dir_cmd.msgid,
             self._invert_dir, self._oid),
                                       self._ffi_lib.stepcompress_free)
+        self._mcu.register_stepqueue(self._stepqueue)
     def get_oid(self):
         return self._oid
     def set_position(self, pos):
@@ -417,7 +417,7 @@ class MCU:
         ffi_main, self._ffi_lib = chelper.get_ffi()
         self._max_stepper_error = config.getfloat(
             'max_stepper_error', 0.000025, minval=0.)
-        self._steppers = []
+        self._stepqueues = []
         self._steppersync = None
         # Print time to clock epoch calculations
         self._print_start_time = 0.
@@ -617,9 +617,9 @@ class MCU:
                 "MCU config: %s" % (" ".join(
                     ["%s=%s" % (k, v) for k, v in msgparser.config.items()]))]
             self._printer.bglogger.set_rollover_info("mcu", "\n".join(info))
-        stepqueues = tuple(s._stepqueue for s in self._steppers)
         self._steppersync = self._ffi_lib.steppersync_alloc(
-            self.serial.serialqueue, stepqueues, len(stepqueues), move_count)
+            self.serial.serialqueue, self._stepqueues, len(self._stepqueues),
+            move_count)
         for c in self._init_cmds:
             self.send(self.create_command(c))
     # Config creation helpers
@@ -644,8 +644,8 @@ class MCU:
             self._config_cmds.append(cmd)
     def register_msg(self, cb, msg, oid=None):
         self.serial.register_callback(cb, msg, oid)
-    def register_stepper(self, stepper):
-        self._steppers.append(stepper)
+    def register_stepqueue(self, stepqueue):
+        self._stepqueues.append(stepqueue)
     def alloc_command_queue(self):
         return self.serial.alloc_command_queue()
     def lookup_command(self, msgformat):