Device or resource busy running on Raspberry 4

[AlanAlex-AR]

We are running the run controller.py example on a Raspberry 4 but we get the following error

sudo python3 ble.py DC:A6:32:68:FA:17 device.json hci-socket:0
DEBUG:asyncio:Using selector: EpollSelector
>>> connecting to HCI...
Traceback (most recent call last):
  File "/home/kenko/Documents/Kabanta/Kabanta/Proy_graph/ble.py", line 251, in <module>
    asyncio.run(main())
  File "/usr/lib/python3.9/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib/python3.9/asyncio/base_events.py", line 642, in run_until_complete
    return future.result()
  File "/home/kenko/Documents/Kabanta/Kabanta/Proy_graph/ble.py", line 197, in main
    async with await open_transport_or_link(sys.argv[3]) as (hci_source, hci_sink):
  File "/usr/local/lib/python3.9/dist-packages/bumble/transport/__init__.py", line 182, in open_transport_or_link
    return await open_transport(name)
  File "/usr/local/lib/python3.9/dist-packages/bumble/transport/__init__.py", line 74, in open_transport
    return _wrap_transport(await _open_transport(name))
  File "/usr/local/lib/python3.9/dist-packages/bumble/transport/__init__.py", line 131, in _open_transport
    return await open_hci_socket_transport(spec[0] if spec else None)
  File "/usr/local/lib/python3.9/dist-packages/bumble/transport/hci_socket.py", line 93, in open_hci_socket_transport
    raise IOError(ctypes.get_errno(), os.strerror(ctypes.get_errno()))
OSError: [Errno 16] Device or resource busy

I can see the controller using hciconfig

hci0:	Type: Primary  Bus: UART
	BD Address: DC:A6:32:68:FA:17  ACL MTU: 1021:8  SCO MTU: 64:1
	UP RUNNING PSCAN 
	RX bytes:2241 acl:0 sco:0 events:119 errors:0
	TX bytes:5095 acl:0 sco:0 commands:119 errors:0
	Features: 0xbf 0xfe 0xcf 0xfe 0xdb 0xff 0x7b 0x87
	Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
	Link policy: RSWITCH SNIFF 
	Link mode:hci0:	Type: Primary  Bus: UART
	BD Address: DC:A6:32:68:FA:17  ACL MTU: 1021:8  SCO MTU: 64:1
	UP RUNNING PSCAN 
	RX bytes:2241 acl:0 sco:0 events:119 errors:0
	TX bytes:5095 acl:0 sco:0 commands:119 errors:0
	Features: 0xbf 0xfe 0xcf 0xfe 0xdb 0xff 0x7b 0x87
	Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
	Link policy: RSWITCH SNIFF 
	Link mode: SLAVE ACCEPT 
	Name: 'raspberrypi'
	Class: 0x7c0000
	Service Classes: Rendering, Capturing, Object Transfer, Audio, Telephony
	Device Class: Miscellaneous, 
	HCI Version: 5.0 (0x9)  Revision: 0x17e
	LMP Version: 5.0 (0x9)  Subversion: 0x6119
	Manufacturer: Cypress Semiconductor (305) SLAVE ACCEPT 
	Name: 'raspberrypi'
	Class: 0x7c0000
	Service Classes: Rendering, Capturing, Object Transfer, Audio, Telephony
	Device Class: Miscellaneous, 
	HCI Version: 5.0 (0x9)  Revision: 0x17e
	LMP Version: 5.0 (0x9)  Subversion: 0x6119
	Manufacturer: Cypress Semiconductor (305)

[Gilles Boccon-Gibod]

When using the built-in controller on the RPi, you need exclusive access to it, so you need to first disable the native Bluetooth stack, which claims the device by default. You can read about the details here: https://google.github.io/bumble/platforms/linux.html#using-hci-sockets
(see the "Disabling bluetoothd" section)