Add timeouts to bus devices. #51
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| if self.timeout is not None: | ||
| lock_start_time = time.monotonic() |
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Suggestion: use time.monotonic_ns() throughout as it'll avoid issues with floating point precision when the program runs for a long time.
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| def __init__(self, i2c, device_address, probe=True): | ||
| def __init__(self, i2c, device_address, probe=True, timeout=0.25): |
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Can you add the timeout parameter to the docstring above here?
adafruit_bus_device/i2c_device.py
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| lock_start_time = time.monotonic() | ||
| while not self.i2c.try_lock(): | ||
| if self.timeout > (time.monotonic() - lock_start_time): | ||
| raise Exception("'I2CDevice' lock timed out") |
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Don't raise bare Exceptions. It seems other Adafruit libraries use RuntimeError here. source.
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I am not sure what problem this is trying to solve. If you are seeing hangs on I2C devices, we have an issue open to solve that problem at a lower level. See adafruit/circuitpython#2253. I have plans to fix this at some point.
adafruit_bus_device/i2c_device.py
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| def __init__(self, i2c, device_address, probe=True, timeout=0.25): | ||
| def __init__(self, i2c, device_address, probe=True, timeout=250): |
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Please go back to floating point seconds. We are trying to be uniform and always use float seconds.
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The I2C bus hangs mentioned in that issue cannot be solved with timeouts in Python; timeouts have to be added in the C code at a low level where the bus status is checked. |
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This issue needs to be fixed in the CircuitPython core, not the bus_device library. I'm closing this in favor of adafruit/circuitpython#2253 |
4 participants
I noticed that on some devices (so far only nrf52840s) after many reboots all hardware locking hangs indefinitely. This modification adds timeouts to the bus devices (default of .25 seconds to be generous) where it will only try to lock for up to the specified amount of time. the timeout can be deactivated by passing
Noneas the timeout. if the time runs out an exception of typeexceptionis thrown.this code was tested on hardware similar to the feather nrf52840