The kernel appears to add the device first without any parents,
then to move it to the correct place in the hierarchy, with its
immediate parent being the device's HCI controller. So we need
to capture the 'move' event too since that's when the rfcomm
device is finally usable.
Ignore devices that aren't completely configured by udev yet. If
ModemManager is started in parallel with udev, explicitly requesting
devices may return devices for which not all udev rules have yet been
applied (a bug in udev/gudev). Since we often need those rules to match
the device to a specific ModemManager driver, we need to ensure that all
rules have been processed before handling a device.
Do this by adding an item to the environment of each device that MM
might possibly be interested in, and ignoring devices that don't
have that. When the device is fully processed by udev, MM will get
an 'add' event and the device will have all rules applied.
Dan Williams