MLIA-460 Revisit backend management

- Provide command for backend installation in case
  if backend is not available
- Fix issue with connection timeout during downloading
- Show installation tools output only in verbose mode

Change-Id: Ic0e495ba19879cc2cda4fd0bce20b57ba896cfeb

2 files changed, 15 insertions, 3 deletions

diff --git a/src/mlia/backend/errors.py b/src/mlia/backend/errors.py
new file mode 100644
index 0000000..bd5da95
--- /dev/null
+++ b/src/mlia/backend/errors.py
@@ -0,0 +1,12 @@
+# SPDX-FileCopyrightText: Copyright 2022, Arm Limited and/or its affiliates.
+# SPDX-License-Identifier: Apache-2.0
+"""Backend errors."""
+
+
+class BackendUnavailableError(Exception):
+    """Backend unavailable error."""
+
+    def __init__(self, msg: str, backend: str) -> None:
+        """Init error."""
+        super().__init__(msg)
+        self.backend = backend
diff --git a/src/mlia/backend/tosa_checker/compat.py b/src/mlia/backend/tosa_checker/compat.py
index e1bcb24..bd21774 100644
--- a/src/mlia/backend/tosa_checker/compat.py
+++ b/src/mlia/backend/tosa_checker/compat.py
@@ -8,6 +8,7 @@ from typing import Any
 from typing import cast
 from typing import Protocol
 
+from mlia.backend.errors import BackendUnavailableError
 from mlia.core.typing import PathOrFileLike
 
 
@@ -45,9 +46,8 @@ def get_tosa_compatibility_info(
     checker = get_tosa_checker(tflite_model_path)
 
     if checker is None:
-        raise Exception(
-            "TOSA checker is not available. "
-            "Please make sure that 'tosa-checker' backend is installed."
+        raise BackendUnavailableError(
+            "Backend tosa-checker is not available", "tosa-checker"
         )
 
     ops = [