Galaxy Book2 Pro with Intel Arc graphics (XEE version), power usage and s2idle sleep
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Summary
The A350M GPU consumes several watts of power even when idle. Furthermore, it prevents the CPU from sleeping, and also causes excessive battery drain and heat in s2idle sleep (deep sleep does not seem to work in this laptop).
Workaround
Disable the discrete GPU by creating a file /etc/modprobe.d/no-dg2.conf
with the line
options i915 force_probe=!5694
reboot to apply changes.
Results
The battery drain (as reported by powertop) goes from ~15 watts idle to less than 4. The laptop does not heat up (before it was making the keyboard uncomfortably warm) and it does not drain battery during sleep.
Further information
Operating system
I tried Arch Linux, Artix, Xubuntu LTS and normal Xubuntu.
Observations
- For some reason Xubuntu was idling at around 8W without any changes and Arch/Artix at around 15-17.
- Linux 6.4 kernel in Arch had some issue loading the intel graphics driver and there I could see a much lower power usage, even if Mesa was using CPU (llvmpipe) for rendering. This was the first hint it was a GPU issue.
- The Arc GPU was in theory not being.
- Powertop would show ~55% usage of the A350 even when the device was supposed to be idle.
- CPU would only spend ~30% or less in C8 PKG state.
Other things tried
- Setting all PCI devices to
auto
and enabling ASPM (even with superpowersave), while helpful, did not solve the issue. - Disabling the PEGP, etc interrupts (related to the ARC device) in
/proc/acpi/wakeup
did solve the power drain issue in s2idle. I also setec_no_wakeup
but I doubt that was required (it was not harmful either). - Using the
linux-drm-xe-next-git
kernel from Intel (XE driver instead if i915) did not work either. - Removing/disabling the device via sysfs had no effect.
intel_pm_rpm --force-d3cold-wait
says it is waiting for the device to enter the d3cold state but it does not enter.
Final Remarks
It is no great of a loss to disable this card. It is actually slightly less powerful than the built in Iris Xe and the "Deep Link" does not seem to be supported in Linux.
I was prepared to sell this laptop and go back to my old Notebook 9, had I not solved this issue.