In-Use Glasgows can be interrupted by firmware reload

I had previously started a Glasgow collecting data using the SCD30 applet.

I’ve just connected a second Glasgow to my system and ran glasgow list (to get the serial for use with --serial), and noticed that the SCD30 Glasgow was interrupted. I also think I saw the following line twice (once for each board, I’ve lost the output unfortunately).

I: g.device.hardware: found revC1 device with API level 0 (supported API level is 1)

It seems that running glasgow list reloaded the firmware on the currently busy board, interrupting the applet, and showing the errors below (the last a number of times).

I don’t know if we can “lock” a device, or determine if it is already use, but this may be worth investigating.

The API level message was introduced in ab21295, and may or may not be related.

I’ll look into this further when I have time.

---

Traceback (most recent call last):
  File "/home/attie/proj_local/glasgow/venv/bin/glasgow", line 11, in <module>
    load_entry_point('glasgow', 'console_scripts', 'glasgow')()
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/cli.py", line 830, in main

  File "/home/attie/.bin/python3.8.2/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/cli.py", line 639, in _main
    await asyncio.wait(tasks, return_when=asyncio.ALL_COMPLETED)
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/cli.py", line 600, in run_applet
    if args.action == "run":
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/sensor/scd30/__init__.py", line 290, in interact
    await asyncio.wait_for(report(), meas_interval * 3)
  File "/home/attie/.bin/python3.8.2/lib/python3.8/asyncio/tasks.py", line 483, in wait_for
    return fut.result()
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/sensor/scd30/__init__.py", line 283, in report
    while not await scd30.is_data_ready():
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/sensor/scd30/__init__.py", line 96, in is_data_ready
    ready, = await self._read(CMD_DATA_READY, ">H")
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/sensor/scd30/__init__.py", line 81, in _read
    return struct.unpack(format, await self._read_raw(addr, struct.calcsize(format)))
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/sensor/scd30/__init__.py", line 54, in _read_raw
    acked = await self.lower.write(self.i2c_addr, struct.pack(">H", addr), stop=True)
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/interface/i2c_initiator/__init__.py", line 182, in write
    acked = len(data) - unacked
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/applet/interface/i2c_initiator/__init__.py", line 163, in _data_read

  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/access/direct/demultiplexer.py", line 225, in read
    async def read(self, length=None, *, flush=True):
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/access/direct/demultiplexer.py", line 357, in flush
    if self._out_buffer:
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/support/task_queue.py", line 73, in wait_all
    async def wait_all(self):
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/support/task_queue.py", line 55, in poll
    """
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/access/direct/demultiplexer.py", line 288, in _out_task

  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/device/hardware.py", line 245, in bulk_write
    else:
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/device/hardware.py", line 204, in _do_transfer
    def close(self):
  File "/home/attie/proj_local/glasgow/venv/lib/python3.8/site-packages/usb1/__init__.py", line 822, in submit
    raiseUSBError(result)
  File "/home/attie/proj_local/glasgow/venv/lib/python3.8/site-packages/usb1/__init__.py", line 125, in raiseUSBError
    raise __STATUS_TO_EXCEPTION_DICT.get(value, __USBError)(value)
usb1.USBErrorNoDevice: LIBUSB_ERROR_NO_DEVICE [-4]
E: asyncio: Unclosed client session
client_session: <aiohttp.client.ClientSession object at 0x7f98fa2d97f0>
E: asyncio: Task exception was never retrieved
future: <Task finished name='Task-2297363' coro=<DirectDemultiplexerInterface._in_task() done, defined at /home/attie/proj_local/glasgow/glasgow/software/glasgow/access/direct/demultiplexer.py:209> exception=Gla
sgowDeviceError('transfer error: LIBUSB_TRANSFER_ERROR')>
Traceback (most recent call last):
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/access/direct/demultiplexer.py", line 217, in _in_task
    await self._in_pushback.wait()
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/device/hardware.py", line 236, in bulk_read
    endpoint_dir = "OUT"
  File "/home/attie/proj_local/glasgow/glasgow/software/glasgow/device/hardware.py", line 206, in _do_transfer
    self.usb_handle.close()
glasgow.device.GlasgowDeviceError: transfer error: LIBUSB_TRANSFER_ERROR

[whitequark]

Actually, I think I came up with a way that is somewhat simpler and works with every firmware version we have: just try to claim every interface that is already exposed before reflashing, then release. (AIUI, on Windows libusb requires exclusive access in first place, so this is never an issue, and on Linux at least one of these claims must fail if the device is in use.)

[whitequark]

Per IRC discussion, it’s an edge case that we probably can’t do much with.