laikad: use cython version of gnss kf

selfdrive/locationd/laikad.py

@@ -138,7 +138,7 @@ class Laikad:
       self.gnss_kf.predict(t)
 
   def kf_valid(self, t: float) -> List[bool]:
-    filter_time = self.gnss_kf.filter.filter_time
+    filter_time = self.gnss_kf.filter.get_filter_time()
     return [filter_time is not None,
             filter_time is not None and abs(t - filter_time) < MAX_TIME_GAP,
             all(np.isfinite(self.gnss_kf.x[GStates.ECEF_POS]))]

selfdrive/locationd/models/gnss_kf.py

@@ -3,12 +3,16 @@ import sys
 from typing import List
 
 import numpy as np
-import sympy as sp
 
-from rednose.helpers.ekf_sym import EKF_sym, gen_code
 from selfdrive.locationd.models.constants import ObservationKind
 from selfdrive.locationd.models.gnss_helpers import parse_pr, parse_prr
 
+if __name__ == '__main__':  # Generating sympy
+  import sympy as sp
+  from rednose.helpers.ekf_sym import gen_code
+else:
+  from rednose.helpers.ekf_sym_pyx import EKF_sym  # pylint: disable=no-name-in-module
+
 
 class States():
   ECEF_POS = slice(0, 3)  # x, y and z in ECEF in meters