- The AC adapter now shows up in power management apps
- Instead of reporting 8Wh total energy, it now reads customizable battery full energy from devicetree.
- … which allows better remaining time estimation
- Device current energy logic is also updated.
- Reports current power rate, no more upowerd warnings about “battery discharging at -0.000000W”
- Exposes sysfs node `/sys/class/power_supply/axp20x-battery/calibrate
- Write 1 to the file to initiate battery full capacity calibration
- Read from the file:
- 0: calibration disabled
- 32: calibration enabled, but not active
- 48: calibration in progress
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Fabulous! Any chance you can implement some of the other features too? (charge termination voltage/current, led indicator behavior, etc) 
I believe these are already there:
yatli@devterm /sys/class/power_supply/axp20x-battery % ls
calibrate constant_charge_current_max energy_full health power status uevent voltage_now
capacity current_now energy_full_design hwmon2 power_now subsystem voltage_max_design wakeup6
constant_charge_current device energy_now online present type voltage_min_design
R/W entries are:
- calibrate
- constant_charge_current_max
- constant_charge_current
- voltage_max_design
- voltage_min_design
- status (0=disables charging)
All power/current/voltage metrics are in micro-lets. 
Edit: maybe one missing piece, the end charge current. I’ll see if the linux power supply model has something equivalent.
Edit: nope, need a custom sysfs node for that.
Where do you get the i2c commands? 
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Whoa! I didn’t those could be set… time to experiment!
- voltage_min_design: 2.6v to 3.3v in 0.1v increments
- voltage_max_design: either 4.1v or 4.2v (?!?)
- constant_charge_current: 300mA to 2100mA in 150mA increments
- constant_charge_current_max: 300mA to 2100mA in 150mA increments
- status: my stock manjaro kernel only seems to accept Charging, 1, 2, and 3…
– 2 and 3 stops charging.
I used the AXP228 datasheet, a calculator, and pen and paper. It was my first time with both i2cset and bitmasks, and it was pretty fun 
Also, don’t forget the blinky charge led!
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