Use 'device_db' for device database updates. Change the sony driver as appropriate. Remove the tweak.

resources/default_tweaks.py

@@ -180,13 +180,3 @@ content_server_wont_display = ['']
 # level sorts, and if you are seeing a slowdown, reduce the value of this tweak.
 maximum_resort_levels = 5
 
-
-# Tell the Sony driver to apply the plugboard specified by the given format
-# before writing to its database. This can be used to change the title, etc,
-# in the DB, and therefore what the Sony displays.
-# Example:
-# sony_db_use_plugboard_format='epub'
-# Apply the epub plugboard before writing to the Sony DB.
-# Default: ''
-sony_db_use_plugboard_format=''
-

src/calibre/devices/prs505/driver.py

@@ -167,10 +167,8 @@ class PRS505(USBMS):
         debug_print('PRS505: finished rebuild_collections')
 
     def use_plugboard_ext(self):
-        ext = tweaks.get('sony_db_use_plugboard_format', None)
+        return 'device_db'
-        return ext
 
     def set_plugboard(self, pb):
-        if tweaks.get('sony_db_use_plugboard_format', None):
         debug_print('PRS505: use plugboard', pb)
         self.plugboard = pb

src/calibre/gui2/preferences/plugboard.py

@@ -60,6 +60,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         for w in metadata_writers():
             for f in w.file_types:
                 self.formats.append(f)
+        self.formats.append('device_db')
         self.formats.sort()
         self.formats.insert(1, plugboard_any_format_value)
         self.new_format.addItems(self.formats)