[Power Management] High battery drain during suspend on MacBook Air M2 (Ubuntu Asahi)

[toshithh]

System Information

• Device: MacBook Air with Apple M2 chip
• Distro: Ubuntu Asahi (based on Ubuntu 24.04)
• Kernel: 6.14.0-1001-asahi-arm
• Desktop Environment: GNOME

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Summary

When I suspend the system (via lid close or UI), my MacBook continues to drain battery at a high rate — even more than it does when left idle with the screen off. This suggests that suspend is not functioning as a proper low-power state.

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Details

• cat /sys/power/mem_sleep shows:

[s2idle]

• There is no /proc/acpi/wakeup, which I understand is expected on Apple Silicon.
• It appears the system is using s2idle, which does not properly power down hardware components.
• Battery loss during suspend (over 8 hours):
  • Screen off (idle): ~3–5% drain
  • Suspend (systemctl suspend or lid close): ~15–20% drain
• Hibernate does not appear functional either.

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What I’ve Tried

• Disabled automatic suspend via logind.conf
• Used xset dpms force off as a workaround to blank the screen
• Applied powertop --auto-tune and TLP for general power saving
• Confirmed I’m on a recent Asahi-enabled kernel (6.14.0-1001-asahi-arm)

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Expected Behavior

Suspend should significantly reduce battery usage, ideally close to what macOS does during sleep (1–2% over 8 hours). Right now, it behaves closer to an idle state with the display off — not true suspend-to-RAM.

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Questions

1. Is this the expected behavior on Apple M2 right now?
2. Are there plans to support deeper sleep states (like s2idle → deep) on M1/M2 in upcoming kernel versions?
3. Is there a workaround or patch I can test to reduce power draw while suspended?

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Thank you for all the work you've done on Apple Silicon support. I’m happy to test experimental features or provide logs if needed.

[eslerm]

Thanks for reporting. Please refer to AsahiLinux/linux#262 as this is also an upstream issue.