mpm: x4xx: Fix clock/time source API

In f73e327, we modified PeriphManagerBase to explicitly list all
required methods as per the MPM/UHD API. This had an unintended side
effect: Because the clocking methods on x4xx are imported from
X4xxClockMgr, and not defined on x4xx itself, the method used to import
methods from X4xxClockMgr onto x4xx would refuse to re-define API calls
such as set_clock_source(), get_clock_source(), and so on.

The solution is to allow _add_public_methods() to overwrite existing
methods, which means we can overwrite abstract methods from
PeriphManagerBase in this fashion.

Without this patch, UHD sessions could fail in the following manner:

>>> import uhd
>>> U = uhd.usrp.MultiUSRP("type=x4xx")
>>> U.get_clock_source(0)
Traceback (most recent call last):
File "<input>", line 1, in <module>
U.get_clock_source(0)
RuntimeError: RuntimeError: Error during RPC call to `get_clock_source'.
Error message: get_clock_source() not available on this device!

2 files changed, 6 insertions, 3 deletions

diff --git a/mpm/python/usrp_mpm/periph_manager/base.py b/mpm/python/usrp_mpm/periph_manager/base.py
index ff4a358b3..729952c33 100644
--- a/mpm/python/usrp_mpm/periph_manager/base.py
+++ b/mpm/python/usrp_mpm/periph_manager/base.py
@@ -659,7 +659,7 @@ class PeriphManagerBase(object):
             self.dboards.append(db_class(dboard_idx, **dboard_info))
         self.log.info("Initialized %d daughterboard(s).", len(self.dboards))
 
-    def _add_public_methods(self, src, prefix="", filter_cb=None):
+    def _add_public_methods(self, src, prefix="", filter_cb=None, allow_overwrite=False):
         """
         Add public methods (=API) of src to self. To avoid naming conflicts and
         make relations clear, all added method names are prefixed with 'prefix'.
@@ -677,6 +677,8 @@ class PeriphManagerBase(object):
         :param prefix: method names in dest will be prefixed with prefix
         :param filter_cb: A callback that returns true if the method should be
                           added. Defaults to always returning True
+        :param allow_overwrite: If True, then methods from src will overwrite
+                                existing methods on self. Use with care.
         """
         filter_cb = filter_cb or (lambda *args: True)
         assert callable(filter_cb)
@@ -691,7 +693,7 @@ class PeriphManagerBase(object):
                      and filter_cb(name, getattr(src, name))
                      ]:
             destname = prefix + name
-            if hasattr(self, destname):
+            if hasattr(self, destname) and not allow_overwrite:
                 self.log.warn("Cannot add method {} because it would "
                               "overwrite existing method.".format(destname))
             else:
diff --git a/mpm/python/usrp_mpm/periph_manager/x4xx.py b/mpm/python/usrp_mpm/periph_manager/x4xx.py
index 7479874dc..e72b2e41e 100644
--- a/mpm/python/usrp_mpm/periph_manager/x4xx.py
+++ b/mpm/python/usrp_mpm/periph_manager/x4xx.py
@@ -484,7 +484,8 @@ class x4xx(ZynqComponents, PeriphManagerBase):
         self._add_public_methods(
             self._clk_mgr,
             prefix="",
-            filter_cb=lambda name, method: not hasattr(method, '_norpc')
+            filter_cb=lambda name, method: not hasattr(method, '_norpc'),
+            allow_overwrite=True
         )
 
         # Overlay must be applied after clocks have been configured