PinePhone: Screen sometimes start flipping between two frames on OpenGL surfaces while performing CPU-heavy tasks

Describe your issue

What's the expected behaviour?

User interface stays responsive.

What's the current behaviour?

Sometimes when performing CPU-heavy tasks, Phosh/Phoc gets into a weird state where it only replays the last few frames that were displayed over and over. When it happened to me while watching a video on YouTube, the audio continued playing normally for a while until it froze, and then started playing again. I am not sure if the few frames kept repeating throughout this as I turned the screen off with the power button earlier and couldn't get the phone to wake up.

By connecting a mouse and keyboard I was able to switch tty and log in there and get the output of dmesg (unfortunately I forgot to check xsession-errors). This output can be found below.

I have also had this happen while installing openjdk8 via apk (sudo apk add openjdk8).

Also perhaps worth noting is that I only have had this happen while on battery power.

Side note: After restarting LightDM (but not the entire phone) Phosh was responsive again although it kept throwing me back to LightDM whenever the screen went dark, however I'd guess that's an unrelated issue. Also, after logging in on LightDM once or twice I got graphical glitches on the screen that looked like dead pixels (but went away once I shut the phone down).

How to reproduce your issue?

1. Perform a CPU-intensive task, like watching a video or installing a big package
2. Either have it succeed or have your phone start replaying the last few frames it showed before the "freeze" happened

What device are you using?

• pine64-pinephone

On what postmarketOS version did you encounter the issue?

• edge (master branch)
• stable (v20.05 branch)

On what environment did you encounter the issue?

Phone environments

• Phosh
• Plasma Mobile
• Sxmo

Other

• No environment
• GNOME
• KDE Plasma
• Kodi
• MATE
• Shelli
• Sway
• Weston
• Xfce4
• fbkeyboard
• i3wm

How did you get postmarketOS image?

• from https://images.postmarketos.org
• I built it using pmbootstrap
• It was preinstalled on my device

Additional information

dmesg output and .xsession-errors after having the issue occur and subsequently switching to a different tty (by plugging in a mouse and keyboard via the dock) after waiting for a while in hopes it would recover: pinephone-phosh-dmesg.log xsession-errors

Issue in deprecated Freedesktop repo: https://gitlab.freedesktop.org/lima/linux/-/issues/33