fix: battery runtime estimation with negative sysfs values #3942
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Some drivers (example: qualcomm-battmgr, present on Snapdragon X1 laptops) expose the current_now and power_now values in sysfs as negative int when the device is discharging, positive when charging. This breaks the battery runtime estimation in Waybar, as it expects a uint32 for power_now. Change the battery module to use the absolute values of current_now and power_now.
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Some drivers (example: qualcomm-battmgr, present on Snapdragon X1 laptops) expose the current_now and power_now values in sysfs as negative int when the device is discharging, positive when charging.
This breaks the battery runtime estimation in Waybar, as it expects a uint32 for power_now.
Change the battery module to use the absolute values of current_now and power_now.
I discussed about it with the maintainer of qualcomm-battmgr, and the conclusion has been that it's better to fix the userland tools to respect the ABI documentation for current_now (which specifies negative values when discharging), and allows for negative values for power_now: https://lore.kernel.org/linux-arm-msm/20250213-patch-qcomm-bat-uint-power-v1-1-16e7e2a77a02@mailbox.org/