4

Situation:

  • Raspberry Pi 3B running freshly flashed Buster SD card.
  • Graphics: Pi => hdmi-to-VGA => monitor.
  • Pi and monitor are on same power strip. Both turn off together once pi has shutdown.
  • Updated, upgraded and autoremoved. No dpkg errors.
  • OpenGL with fake KMS has been enabled via raspi-config.
  • Rebooted.

Problems result:

mouse jitter

  • More RAM used. (250 MB instead of 130 MB.)
  • Entire screen freezes at random times, even when there is plenty free RAM and cpu usage is low.
  • Strange artifacts appear such as this one:
    artifacts in chromium
  • Sometimes it incorrectly guesses the screen resolution on boot (800x600 instead of 1280x1024)enter image description here
    Notice the black space on the left, and cut off on the right.
    Strangely, a reboot doesn't fix it! I have to shutdown and turn off the power strip for the screen resolution to be correct next time.

I attribute all of the above problems to openGL being on, because when it is off, none of these problems have ever occurred.

  1. Has anyone experienced any of these problems before?
  2. If so, did you find any solutions besides turning openGL off?
  3. If not, any ideas why I am the only one?
  • The increased memory footprint is expected and that's one of the reasons they don't support GL on a Pi Zero, but the other stuff we probably need to troubleshoot. When you get the squished text requiring a hard power cycle to fix, is glxinfo still reporting Broadcom V3D or by chance are you in that GPU bad state where it can only do softpipe? Also, what desktop manager is this with the Windows icon in the bottom left and all? – jdonald Sep 11 at 2:18
  • glxinfo: command not found I am using Raspbian's default desktop manager, window manager, and everything else, but used lxappearance to change the look and feel. – Botspot Sep 11 at 12:05
  • Had to install mesa-utils to run glxinfo. Output is here. – Botspot Sep 11 at 12:32
  • Firefox Send download is stuck here: github.com/mozilla/send/issues/1397 Can you use an alternative pastebin? – jdonald Sep 11 at 22:58
  • 1
    If I had to bet I'd say part of the equation is the hdmi-to-VGA connector, ie., plugged into an actual HDMI display you won't have the problem. – goldilocks Sep 12 at 17:46
2

I have reached a partial solution for each of my original points.

  • Mouse pointer jittering/bouncing/jumping/flickering: No known solution, but some /boot/config.txt flags make it more noticeable.
  • More RAM used: Well too bad, turn on swap if necessary.
  • Entire screen freezing: turns out it was related to low voltage, but only occurred when GL was turned on.
  • Strange artifacts: No idea why this happens, it even occurred twice for me on unmodified Buster! Could be related to low voltage, or my installation.
  • Incorrect screen resolution: Turns out it was the VGA adapter. Never happened once on my HDMI monitor.
  • Also found out that the screen and Pi being on the same power strip contributed to incorrect screen resolution. If I plug in the screen, then plug in the Pi 5 seconds later, it would auto-detect the resolution correctly every time. Also explains why slower SD cards never had this problem: the Pi took longer to boot, so the screen had time to initialize. – Botspot Sep 20 at 12:12
1
+100

Pi => hdmi-to-VGA => monitor

Keep in mind that this conversion:

  • May involve a loss of meta-information/control that is otherwise present with HDMI.
  • Degrades the signal in terms of strength; with earlier model Pis, that had a subpar strength HDMI signal to start with, some people found some converters unusable because of this.

If you combine those two factors, it might explain why OGL causes a problem, especially if the corresponding GPU activity affects the signal strength and/or characteristics.

Regardless of the explanation, you can rule this in or out by trying directly with an HDMI monitor.

  • Yes, (see my answer) using a hdmi screen got rid of the incorrect resolution. Well, you get the bounty! – Botspot Sep 18 at 3:11

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