> On Jul 3, 2025, at 7:47 AM, Hans de Goede <hansg@xxxxxxxxxx> wrote: > > Hi Matthew, > >> On 3-Jul-25 3:54 AM, Matthew Schwartz wrote: >> Hello, >> >> I installed kernel 6.15.4 to find that my battery estimate on my handheld gaming device was completely inaccurate, instead giving negative values and an unknown estimated battery life in multiple places. >> >> After bisecting, I landed on "ACPI: battery: negate current when discharging” as the bad commit. This commit breaks not one but several userspace implementations of battery monitoring: Steam and MangoHud. Perhaps it breaks more, but those are the two I have noticed so far. > > Thank you for reporting this. > > As Rafael already indicated this patch will need to be reverted to > unbreak userspace. > > But, the patch was actually doing the right thing, according to: > > Documentation/ABI/testing/sysfs-class-power > > What: /sys/class/power_supply/<supply_name>/current_avg > Date: May 2007 > Contact: linux-pm@xxxxxxxxxxxxxxx > Description: > Battery: > ... > Access: Read > > Valid values: Represented in microamps. Negative values are > used for discharging batteries, positive values for charging > batteries and for USB IBUS current. > > (and the same for current_now) > > and there are many power_supply fuel-gauge drivers (1) under > drivers/power/supply/ which do adhere to this specification > and report a negative current for discharging. > > So if any of the userspace consumers of this API you mention > were to run on hw with these drivers the same problem will > be hit. Can you please file bugs against these userspace > projects so that they can fix this? Sure, I filed a bug with MangoHud last night about the kernel change breaking the current battery logic so I will mention this concern when updating that issue, and I will also file a new bug with Steam. Thanks, Matt > > Regards, > > Hans > > > > 1) For directly accessing fuel-gauge chips on devices where these > are directly accessible instead of being exposed through ACPI
