The kernel sysfs-class-power specifies charge_control_{start,end}_threshold as a standard way to get and set thresholds for charging. These are supported on some laptops.
I've started on an implementation, so I thought I might as well most it as a WIP merge request. But I have some questions about how/whether UPower should offer the necessary functionality:
- Reading charging thresholds is much the same as any of the other properties that are currently offered. But I suppose setting should require polkit authentication? Is that currently in-scope for UPower?
- Looking at the commit history, it seems UPower used to rely on PolKit, but doesn't any more now that features like suspend have been removed in favor of logind.
- If it isn't appropriate for UPower, would any other daemon be more appropriate? Logind isn't relevant for this sort of thing.
- How should the dbus API be specified? Everything else is defined as a property, but:
- I'm not sure if a settable property would work with authentication though polkit... maybe.
- Only some hardware would support this, so it might be desirable to expose this fact in some way.