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Embedded Linux DISCUSSION
A sensor can be controlled by toggling GPIO lines from userspace, but Linux may already have a subsystem driver for its interface. How should a project choose the implementation without duplicating timing-sensitive behavior in a script?
Reference: Linux kernel: GPIO character-device API (https://docs.kernel.org/userspace-api/gpio/chardev.html).
Check the device's existing bus and subsystem support first. A kernel driver can provide standardized access, resource ownership and integration with power management. The GPIO character-device API is useful, but the kernel documentation advises using appropriate existing subsystem drivers for devices they cover.
If userspace GPIO is appropriate, define direction, polarity, edge handling and line ownership explicitly. Consider the latency and event rate the application must tolerate. A line-event timestamp is not the same as the time a userspace handler gets scheduled to process it.
Test disconnects, process restarts and suspend or resume behavior where applicable. Avoid direct register access that bypasses other drivers' ownership. Keep the exact kernel and libgpiod versions in deployment records so an API migration does not silently change the interface behavior.
