Bluetooth: make LE-only devices add "LE:" as an address prefix

This seems a bit odd, but it actually has three different reasons for it:

 - It's a visual indication of BT LE mode for users

 - the rfcomm code only works with legacy BT support, and if we scan a
   device that only does LE, we want the custom serial code to instead
   automatically fall back on a "emulate serial over LE packets" model.

 - we want rfcomm to remain the default for devices that do both legacy
   BT _and_ LE, but we want people to have the ability to override the
   choice manually.  They can now do so by just editing the address
   field and adding the "LE:" prefix manually, and it automatically gets
   saved for next time.

So while a bit hacky, it's actually a very convenient model that not
only works automatically, but allows the manual override.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

core/qt-ble.cpp

@@ -121,6 +121,16 @@ dc_status_t BLEObject::read(void* data, size_t size, size_t *actual)
 
 dc_status_t qt_ble_open(dc_custom_io_t *io, dc_context_t *context, const char *devaddr)
 {
+	/*
+	 * LE-only devices get the "LE:" prepended by the scanning
+	 * code, so that the rfcomm code can see they only do LE.
+	 *
+	 * We just skip that prefix (and it doesn't always exist,
+	 * since the device may support both legacy BT and LE).
+	 */
+	if (!strncmp(devaddr, "LE:", 3))
+		devaddr += 3;
+
 	QBluetoothAddress remoteDeviceAddress(devaddr);
 
 	// HACK ALERT! Qt 5.9 needs this for proper Bluez operation

desktop-widgets/btdeviceselectiondialog.cpp

@@ -420,7 +420,14 @@ void BtDeviceSelectionDialog::deviceDiscoveryError(QBluetoothDeviceDiscoveryAgen
 QString BtDeviceSelectionDialog::getSelectedDeviceAddress()
 {
 	if (selectedRemoteDeviceInfo) {
-		return selectedRemoteDeviceInfo.data()->address().toString();
+		QBluetoothDeviceInfo *deviceInfo = selectedRemoteDeviceInfo.data();
+		QBluetoothDeviceInfo::CoreConfigurations flags;
+		QString prefix = "";
+
+		flags = deviceInfo->coreConfigurations();
+		if (flags == QBluetoothDeviceInfo::LowEnergyCoreConfiguration)
+			prefix = "LE:";
+		return prefix + deviceInfo->address().toString();
 	}
 
 	return QString();