trezor: minor things for better model "safe 3" support

electrum/plugins/trezor/clientbase.py

@@ -203,7 +203,7 @@ class TrezorClientBase(HardwareClientBase, Logger):
         return self.client.version >= self.plugin.minimum_firmware
 
     def get_trezor_model(self):
-        """Returns '1' for Trezor One, 'T' for Trezor T."""
+        """Returns '1' for Trezor One, 'T' for Trezor T, etc."""
         return self.features.model
 
     def device_model_name(self):
@@ -212,6 +212,8 @@ class TrezorClientBase(HardwareClientBase, Logger):
             return "Trezor One"
         elif model == 'T':
             return "Trezor T"
+        elif model == "Safe 3":
+            return "Trezor Safe 3"
         return None
 
     @runs_in_hwd_thread
@@ -290,10 +292,12 @@ class TrezorClientBase(HardwareClientBase, Logger):
         # check PIN length. Depends on model and firmware version
         # https://github.com/trezor/trezor-firmware/issues/1167
         limit = 9
-        if self.features.model == "1" and (1, 10, 0) <= self.client.version:
+        if self.get_trezor_model() == "1":
-            limit = 50
+            if (1, 10, 0) <= self.client.version:
-        elif self.features.model == "T" and (2, 4, 0) <= self.client.version:
+                limit = 50
-            limit = 50
+        else:
+            if (2, 4, 0) <= self.client.version:
+                limit = 50
         if len(pin) > limit:
             self.handler.show_error(_('The PIN cannot be longer than {} characters.').format(limit))
             raise Cancelled

electrum/plugins/trezor/qt.py

@@ -425,8 +425,15 @@ class InitSettingsLayout(QVBoxLayout):
         if method == TIM_NEW:
             self.cb_no_backup = QCheckBox(_('Enable seedless mode'))
             self.cb_no_backup.setChecked(False)
-            if (model == '1' and fw_version >= (1, 7, 1)
+            supports_no_backup = False
-                    or model == 'T' and fw_version >= (2, 0, 9)):
+            if model == '1':
+                if fw_version >= (1, 7, 1):
+                    supports_no_backup = True
+            else:
+                if fw_version >= (2, 0, 9):
+                    supports_no_backup = True
+            if supports_no_backup:
+                self.cb_no_backup.setEnabled(True)
                 self.cb_no_backup.setToolTip(SEEDLESS_MODE_WARNING)
             else:
                 self.cb_no_backup.setEnabled(False)