The hw_pattern attribute is driver specific. Ensure we don't apply the LED pattern to unknown drivers. Closes: https://source.puri.sm/Librem5/feedbackd/-/issues/77
We prefer the C types in new code.
QCOM LPG LEDs expose a hw_pattern sysfs entry which accepts a limited set of patterns but allows to use dedicated hardware for blinking the LED. This way, battery life can be improved and the LED still blinks, even if the device is suspended.