Prioritize radio-supplied tuning steps

This makes the UI consider the radio's tuning steps, if defined as
the first course of action. The existing code tried the standard
set followed by the radio's set, assuming the radio's would be a
subset, which is of course not always true.

This also makes required_step() consider the radio-specific steps
after the standard ones, if there are any strange ones to allow the
radio to define ones that are not in the standard list.

Related to #10968

chirp/chirp_common.py

@@ -814,6 +814,10 @@ def LIST(v):
     assert hasattr(v, '__iter__')
 
 
+def LIST_NONZERO_INT(v):
+    assert all(x > 0 for x in v)
+
+
 def INT(min=0, max=None):
     def checkint(v):
         assert isinstance(v, int)
@@ -865,7 +869,7 @@ class RadioFeatures:
         "valid_modes":          LIST,
         "valid_tmodes":         LIST,
         "valid_duplexes":       LIST,
-        "valid_tuning_steps":   LIST,
+        "valid_tuning_steps":   LIST_NONZERO_INT,
         "valid_bands":          LIST,
         "valid_skips":          LIST,
         "valid_power_levels":   LIST,
@@ -1736,10 +1740,21 @@ def required_step(freq, allowed=None):
         8.33: is_8_33,
     }
 
+    # Try the above "standard" steps first in order
     for step, validate in steps.items():
         if step in allowed and validate(freq):
             return step
 
+    # Try any additional steps in the allowed list
+    for step in allowed:
+        if step in steps:
+            # Already tried
+            continue
+        if make_is(int(step * 1000))(freq):
+            LOG.debug('Chose non-standard step %s for %s' % (
+                step, format_freq(freq)))
+            return step
+
     raise errors.InvalidDataError("Unable to find a supported " +
                                   "tuning step for %s" % format_freq(freq))
 

chirp/wxui/memedit.py

@@ -1337,18 +1337,12 @@ def _set_memory_defaults(self, mem, *only):
         else:
             want_tuning_step = 5.0
             try:
-                # First calculate the needed step in case it is not supported
-                # by the radio. If we fail to find one the radio supports,
-                # we will use this one and then the error message about it
-                # being unsupported will be accurate.
-                want_tuning_step = chirp_common.required_step(mem.freq)
-
-                # Now try to find a suitable one that the radio supports.
+                # Try to find a tuning step for the frequency that the radio
+                # supports, or with the default set
                 want_tuning_step = chirp_common.required_step(
-                    mem.freq, features.valid_tuning_steps)
-                LOG.debug('Chose radio-supported step %s' % want_tuning_step)
+                    mem.freq, features.valid_tuning_steps or None)
             except errors.InvalidDataError as e:
-                LOG.warning(e)
+                LOG.warning('Failed to find step: %s' % e)
 
         if 'tuning_step' in only and want_tuning_step:
             mem.tuning_step = want_tuning_step

tests/unit/test_chirp_common.py

@@ -503,6 +503,11 @@ def test_required_step_finds_suitable(self):
         self.assertEqual(2.5, chirp_common.required_step(self._005[0],
                                                          allowed=[2.5]))
 
+    def test_required_step_finds_radio_specific(self):
+        # Make sure we find a radio-specific step, 10Hz in this case
+        self.assertEqual(0.01, chirp_common.required_step(
+            146000010, allowed=[5.0, 10.0, 0.01, 20.0]))
+
     def test_required_step_fail(self):
         self.assertRaises(errors.InvalidDataError,
                           chirp_common.required_step,