macsmc-power macsmc-power: Emergency notification: Battery status is OK?

[jvoisin]

I'm getting a handful of macsmc-power macsmc-power: Emergency notification: Battery status is OK? messages in my dmesg on my Apple M2 (G14G B0) when the laptop is charging, which is a tad worrying:

# dmesg | tail -n 10
[31732.908521] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[32304.908930] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[32431.908778] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[32577.910139] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[32745.908860] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[32948.909745] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[33190.908861] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[33496.908816] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[33906.908841] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
[33926.909603] macsmc-power macsmc-power: Emergency notification: Battery status is OK?
# dmesg | grep -c 'Emergency notification: Battery status is OK?'
149
# uptime 
 20:53:11 up 1 day, 5 min,  4 users,  load average: 0.32, 0.30, 0.29
# uname -a
Linux chernabog 6.15.10-402.asahi.fc42.aarch64+16k #1 SMP PREEMPT_DYNAMIC Sun Aug 24 15:40:45 UTC 2025 aarch64 GNU/Linux
#

[dkwo]

@jvoisin Are you also unable to read /sys/class/power_supply/macsmc-battery/charge_behaviour ?

[jvoisin]

# cat /sys/class/power_supply/macsmc-battery/charge_behaviour 
cat: /sys/class/power_supply/macsmc-battery/charge_behaviour: Input/output error
[1]
#

yup

[SludgePhD]

Same behavior here on an M1 MacBook Air.

[kevgo]

One important practical effect of this regression might be that limiting the battery charge level to 80% no longer works. I've been setting it using:

echo 'SUBSYSTEM=="power_supply", KERNEL=="macsmc-battery", ATTR{charge_control_end_threshold}="80"' | sudo tee /etc/udev/rules.d/10-battery.rules

This setup worked reliably until an update within the past few weeks.

[kevgo]

Same behavior on Fedora Asahi Remix on MacBook Pro M1 and MacBook Air M2.

[imheresamir]

Same issue on Fedora Asahi Remix on MacBook Pro M2

[allmazz]

+1 on M2 Max 14"

[jmranger]

I strongly suspect that this is the consequence of a firmware change that Apple introduced this summer, published in all MacOS releases starting from September 15 (MacOS 14.8, 15.7, 26).
Multiple MacOS apps that do similar battery charge control had to do code changes to adapt to this:

• AlDente 1.34
• Battery-Toolkit 1.8

The latter is licensed BSD 3-clauses. If it's OK to get inspiration from such code to develop a fix, here's the commit containing the change: mhaeuser/Battery-Toolkit@64c97c

[dkwo]

I just note that tlp is still working for setting charge thresholds, while the asahi-macsmc udev rule is not, due to the kern.err power_supply macsmc-battery: uevent: failed to send synthetic uevent: -5.

[kevgo]

I can confirm that tlp still correctly manages charge thresholds despite the issues described in this ticket. Thanks for the pointer! 🙏

[ealtun21]

I can also confirm that setting the thresholds directly also works, I personally am using a systemd service, as the udev event is not functional.

[jotenakis2]

this bug will not be fixed ?