On Fri, Feb 14, 2025 at 12:24:18AM +0200, Dmitry Baryshkov wrote: > On Thu, Feb 13, 2025 at 05:51:38PM +0100, Anthony Ruhier via B4 Relay wrote: > > From: Anthony Ruhier <aruhier@xxxxxxxxxxx> > > > > The value for the POWER_NOW property is by default negative when the > > battery is discharging, positive when charging. > > > > However on x1e laptops it breaks several userland tools that give a > > prediction of the battery run time (such as the acpi command, powertop > > or the waybar battery module), as these tools do not expect a negative > > value for /sys/class/power_supply/qcom-battmgr-bat/power_now. They > > estimate the battery run time by dividing the value of energy_full by > > power_now. The battery percentage is calculated by dividing energy_full > > by energy_now, therefore it is not impacted. > > > > While having a negative number during discharge makes sense, it is not > > standard with how other battery drivers expose it. Instead, it seems > > standard to have a positive value for power_now, and rely on the status > > file instead to know if the battery is charging or discharging. It is > > what other x86 laptops do. > > Documentation/ABI does not define ABI for the power_now. However for > current_now it clearly defines that it can be positive or negative. > > > > > Without the patch: > > $ acpi > > Battery 0: Discharging, 98%, discharging at zero rate - will never fully discharge. > > > > With the patch: > > $ acpi > > Battery 0: Discharging, 97%, 10:18:27 remaining > > > > --- > > Signed-off-by: Anthony Ruhier <aruhier@xxxxxxxxxxx> > > --- > > drivers/power/supply/qcom_battmgr.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > -- > With best wishes > Dmitry I see. But as it breaks existing tools when power_now is negative, should we change the behavior of these tools or adapt the driver? As it does not seem common that power_now and current_now are negative in other drivers, tools using these values rely on the status anyway. I'm wondering if it provides anything to keep this behavior. -- Regards, Anthony Ruhier
