An alternative approach to MR !253 for fixing BUG: 450551, which makes chargethresholdhelper responsible for persisting charge thresholds (system-wide) instead of PowerDevil::Core and its global .kcfg settings.
This builds but is entirely untested at the moment. Also because I've had trouble with KAuth for some time. I would be surprised if this patch works without extra testing & fixes. That said, I'm not aware of any missing functionality so maybe we're lucky.
Commit message below:
Restore battery charge limits on PowerDevil service startup
The code so far did not persist any charge limits, because itassumed that the firmware would by itself persist them acrossreboots. This was true with many ThinkPads, but is not true anymorewith a growing number of modern laptops that rely on user-spacesoftware to remember and restore threshold values.
This commit modifies the KAuth-powered chargethresholdhelper itself.Calling the setthreshold action will now write a clone of the sysfspower supply battery threshold files to a persistent config path,in addition to writing the settings to sysfs itself.
Secondly, there is a new restorethreshold action which combinesparts of getthreshold and setthreshold to (you guessed it):
- read persisted threshold values,
- and restore them where currently active thresholds differ.
Because chargethresholdhelper runs as root, threshold valuesare shared among different users of the same machine.In effect, this makes it idempotent and works very similar tothe previous assumptions of firmware-persisted thresholds.Barely any changes to PowerDevil itself are needed as a result.
restorethreshold is tame enough to allow unprivileged/passwordlesscalls from within PowerDevil::Core service code.
Existing chargethresholdhelper code got refactored a little tofacilitate these changes. On a high level:
getThresholds()andsetThresholds()get an extra argument tospecify sysfs vs. persistent config directory access.A more complex config system is not needed.- Thresholds are now internally read and set as hashmap of batteryto (start or stop) threshold value, instead of flat array.This helps with applying stored thresholds to current ones,and puts in groundwork for per-battery charge limit support.
getBatteries()only gets called once per action now.More efficient but also will fail more loudly in the unlikelycase of unexpected sysfs directory tree changes.