If the state variable is not updated until mce_signal_callback and
SetProperty(Powered) is called two times quickly, then the second
call will not generate a request to change the radio state of the
MCE if its corresponding call to adapter_powered occurs before the
first triggering of mce_signal_callback.
With this patch two calls to the MCE are executed, although there
might still be an unnecessary power cycle in that
mce_signal_callback is also triggered twice.
Since bluetoothd power cycles the adapter at startup, it is possible
that the plugin gets a reply from reading the state of the MCE and
tries to power the adapter before it is down. The patch checks for
that situation and if it occurs postpones powering the adapter to
the powered state callback.
Registers a callback to btd_adapter to get notified when the
powered state of the adapter is changed. This is needed to update
the state stored in the MCE if the adapter is powered on or off
using for example SetProperty(Powered). The current setting of
the MCE is saved in a variable and if the notification to the
plugin does not match this value the MCE is updated accordingly
using its DBus method for setting radio states.
Adds a plugin for listening to the MCE (Mode Control Entity)
radio state signal. Implemented in a new source file,
configuration flag for enabling it added to the build files.
The plugin registers an adapter driver containing a DBus signal
watch for receiving MCE_RADIO_STATES_SIG messages. On receiving
the signal, it sets the powered state of the adapter according
to the Bluetooth field.
