scripts: check_init_priorities: ignore zephyr,cdc-acm-uart

The new stack zephyr,cdc-acm-uart driver has two separate init path, one
of which kicks in before the USB stack to start buffering log messages.

This generates a false positive in the build time priority checking,
adding a check to ignore that compatible entirely.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>

scripts/build/check_init_priorities.py

@@ -54,6 +54,14 @@
 # opposite of the device tree inferred dependency.
 _INVERTED_PRIORITY_COMPATIBLES = frozenset()
 
+# List of compatibles for nodes where we don't check the priority.
+_IGNORE_COMPATIBLES = frozenset([
+        # This is pre-initialized early to start processing data as soon as
+        # possible, there's a separate SYS_INIT entry running later in the boot
+        # sequence.
+        "zephyr,cdc-acm-uart",
+        ])
+
 class Priority:
     """Parses and holds a device initialization priority.
 
@@ -230,6 +238,10 @@ def _check_dep(self, dev_ord, dep_ord):
         dev_node = self._ord2node[dev_ord]
         dep_node = self._ord2node[dep_ord]
 
+        if dev_node._binding and dev_node._binding.compatible in _IGNORE_COMPATIBLES:
+            self.log.info(f"Ignoring priority: {dev_node._binding.compatible}")
+            return
+
         if dev_node._binding and dep_node._binding:
             dev_compat = dev_node._binding.compatible
             dep_compat = dep_node._binding.compatible

scripts/build/check_init_priorities_test.py

@@ -266,6 +266,8 @@ def test_check_swapped(self, mock_vinit):
         validator.warnings = 0
         validator.errors = 0
 
+        save_inverted_priorities = check_init_priorities._INVERTED_PRIORITY_COMPATIBLES
+
         check_init_priorities._INVERTED_PRIORITY_COMPATIBLES = set([("compat-3", "compat-1")])
 
         validator._ord2node = {1: mock.Mock(), 3: mock.Mock()}
@@ -282,6 +284,39 @@ def test_check_swapped(self, mock_vinit):
             mock.call("Swapped priority: compat-3, compat-1"),
             mock.call("/3 20 > /1 10"),
         ])
+        self.assertEqual(validator.warnings, 0)
+        self.assertEqual(validator.errors, 0)
+
+        check_init_priorities._INVERTED_PRIORITY_COMPATIBLES = save_inverted_priorities
+
+    @mock.patch("check_init_priorities.Validator.__init__", return_value=None)
+    def test_check_ignored(self, mock_vinit):
+        validator = check_init_priorities.Validator("", "", None)
+        validator.log = mock.Mock()
+        validator.warnings = 0
+        validator.errors = 0
+
+        save_ignore_compatibles = check_init_priorities._IGNORE_COMPATIBLES
+
+        check_init_priorities._IGNORE_COMPATIBLES = set(["compat-3"])
+
+        validator._ord2node = {1: mock.Mock(), 3: mock.Mock()}
+        validator._ord2node[1]._binding.compatible = "compat-1"
+        validator._ord2node[1].path = "/1"
+        validator._ord2node[3]._binding.compatible = "compat-3"
+        validator._ord2node[3].path = "/3"
+
+        validator._dev_priorities = {1: 20, 3: 10}
+
+        validator._check_dep(3, 1)
+
+        self.assertListEqual(validator.log.info.call_args_list, [
+            mock.call("Ignoring priority: compat-3"),
+        ])
+        self.assertEqual(validator.warnings, 0)
+        self.assertEqual(validator.errors, 0)
+
+        check_init_priorities._IGNORE_COMPATIBLES = save_ignore_compatibles
 
     @mock.patch("check_init_priorities.Validator._check_dep")
     @mock.patch("check_init_priorities.Validator.__init__", return_value=None)