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WMT OS Linux for WM8505 netbooks |
- Self-calibrating battery driver
- The battery driver has been rewritten around self-calibration. These netbooks gauge their battery by timing an RC circuit whose scale varies from unit to unit, so no shipped constant could fit every board. The driver instead calibrates that scale against the board's fixed low-battery alarm, at the first alarm and again at every later one, and the result persists across reboots and kernel updates. Validated on hardware across four boards and both revisions. The percentage first appears once the battery has drained to the alarm.
- The battery driver now fully supports boards with the older VT1612A codec. The two revisions disagree on the polarity of the charge-complete signal and on the alarm's trip voltage, and an unused WAKEUP3 pin happens to be strapped to opposite levels on each, so the driver reads it to identify the revision and configure both. These boards previously sat at 0% and never reported a completed charge.
- Charge percentages follow a discharge curve measured on real hardware. The vendor's table ran 150 to 250 mV high through the middle of the range, so a battery at a true 30% read closer to 15%.
- GPIO reads from banks 6 through 9 now address the correct input-data register, fixing a bug inherited from the original mainline port. The low-battery alarm pin sits in bank 8.
- Kernel updated to 6.12.101.
- Refreshed standard and desktop images.