Using the webcam on zbook ultra g1a, Linux (ubuntu 25.04)

[MattSchofield]

I've found PCIe Active State Power Management to be causing the instability/freezes with the mt7925 and kernel 6.14.0-1006-oem. I fixed the freeze issue by disabling ASPM.

To disable ASPM, I added the following kernel parameter to my GRUB configuration.

Open the GRUB configuration file with your preferred editor:

nano /etc/default/grub

Find the line starting with GRUB_CMDLINE_LINUX_DEFAULT=. Immediately inside the double quotes, add pcie_aspm=off. For example, if the line was GRUB_CMDLINE_LINUX_DEFAULT="quiet splash", change it to:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=off"

 Save and close the file (Ctrl+S then Ctrl+Q in Xed; Ctrl+O then Enter, then Ctrl+X in Nano).

Update GRUB to apply the changes:

sudo update-grub

Reboot your system for the changes to take effect

After rebooting, you can confirm pcie_aspm=off is active by checking your kernel command line:

cat /proc/cmdline

You should see pcie_aspm=off in the output.

Comparing power usage with Powertop pre and post disabling ASPM I see no difference at all, nor any difference in real world battery life. Also, I can now connect to my phone hotspot.  I don't even understand, but I also don't even care. It didn't work before, it does now.

[jecuendet]

I tried with the pcie_aspm=off parameter. No freeze so far.

But I lost the Ethernet Controller, no more eth0 device....

Do you know which ETH driver it uses?

[MattSchofield]

Jecuendet.  No, sorry.  If pcie_aspm=off caused that, try replacing pcie_aspm=off with pcie_aspm.policy=performance

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm.policy=performance"

Don't forget to update grub

That will keep ASPM enabled but restricts it to less aggressive power saving states, and avoids the power saving transitions that I think are what's causing the freezes.

Please ignore the above.  Freezing occurs with aspm set to performance, when transitioning from low demand to high demand. 

[jecuendet]

I confirm, freeze after some minutes with pcie_aspm=performance

[DougLaptop]

Thank you for this, Matt: 

pcie_aspm=off

Can you please explain how you identified this as the problem? This way, I can improve my own Ubuntu/Linux debugging skills. Appreciate it.

I also found this:

amd_iommu=off

fixed my problem with the 6.11-1025 kernel being unable to wake from sleep.

[MattSchofield]

You won't learn much from me DougLaptop. But I can tell you how I got there all the same.

To start with, the MT7925 was misbehaving with IPv6 traffic. It was unable to route traffic properly when trying to add the Fastfetch PPA.

sudo add-apt-repository ppa:zhangsongcui3371/fastfetch
sudo apt update

GPG error: https://ppa.launchpadcontent.net/... NO_PUBKEY 7E2Ekwndwl865F21
gpg: keyserver receive failed: No route to host

I also tried pinging with IPv6:
ping -6 keyserver.ubuntu.com

And got the following:
From _gateway ... Destination unreachable: Beyond scope of source address

To get around that, I disabled IPv6 on that interface:
echo 'net.ipv6.conf.wlp194s0.disable_ipv6 = 1' | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

...and was able to install Fastfetch. So I knew I'd have to revisit the MT7925 at some point to try and get it working properly, but I could proceed with other things at that point.

I then found I was unable to connect to my phone hotspot. So I decided to try new firmware versions in the hope both Mediatek issues were fixed, both IPv6 and hotspot connectivity hopefully. However, on newer kernels I was having the random freeze issues with every kernel I tried (newer than 6.11), usually when idle or when waking from an idle state. I observed that the freezes were guaranteed when in Power Saver mode, and frequent but not guaranteed in Balanced mode.

With me finding the power state was related to the freezes, I sat and physically observed the stats in Powertop like a neanderthal (I told you you'd learn nothing), to see what the laptop was doing in terms of power usage. It was always when then the power requirements increased after a short idle period that the laptop would freeze. Not a hard crash, it would just become unresponsive to inputs, or occasionally the screen would just go black. ctrl+alt+backspace would usually (but not always) get me back into the session. It never triggered the production of a crash report.

I don't remember exactly how I lucked into it, but I'd Googled something and landed on a Reddit discussion regarding the MT7925 having known issues with ASPM and Runtime PM.  The issue wasn't resolved.  However, given my hotspot connectivity issues and now finding there are known power management issues with the MT7925, I connected the dots and Googled if it was possible to disable ASPM.  And it was.  And here we are.

It hasn't resolved the IPv6 issue, but I can connect to all the hotspots for all the data, and I get no system freezes. Sorry you had to read all that.

[DougLaptop]

You may not have thought I could learn anything, but actually, I learned several interesting things:

1. I learned the WiFi driver name (MT7925)

2. I learned about "powertop"

3. control-alt-backspace - which doesn't seem to do anything for me in Kubuntu-Desktop (maybe it runs Wayland?)

Thanks!