Hi, On Thu, Jul 03, 2025 at 08:51:10AM -0700, Matthew Schwartz wrote: > > 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. I also asked the Collabora team supporting Valve with the Steamdeck to look into it. So I hope that it will be fixed soon :) Thanks for coordinating this Hans. I fully agree with your analysis and middle term plans to revert the revert :) Greetings, -- Sebastian
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