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LRADC Diagnostics and FAQ

  • A key reports its neighbor: remeasure the voltage and increase spacing between ranges.
  • Long-press repeat is abnormal: inspect input repeat settings and driver debounce timing.
  • Intermittent missing events: inspect the resistor ladder, switch contact, ADC input capacitance, and sampling filter.
  • No key responds: verify that the compatible matches the reference-voltage variant and that the node is enabled.
  • Interrupts increase but no event appears: check whether the filter classifies the voltage as an invalid range.

General diagnostic order​

  1. Schematic and power.
  2. Node and pinctrl in the final DTB.
  3. Final .config and modules.
  4. Probe, clock, reset, and IRQ logs.
  5. Device node and sysfs/debugfs.
  6. Minimal functional test.
  7. Stress, suspend, and abnormal hot-plug tests.

Do not treat the removal of an error log as a fix. Find the first failure and validate its upstream and downstream dependencies.