Blank screen shortly after postboot banner with LXDE

Troubleshooting
1

Hello, I recently found out about DietPi by following a GitHub where someone ran MagicMirror on a Pi2W. I got a new Pi2W that I recently bought for this purpose, and due to performance reasons, going with DietPi seems to be the most efficient. Unfortunately, I’ve been having some issues regarding LXDE/Xorg. I’m very new to both Magic Mirror and DietPi stuff, but I believe my issues are related more with DietPi in this case. Essentially, I want to start a Nodejs program (Magic Mirror) via SSH, and then have that display on the local monitor plugged into the Pi (Display 0). As to not diverge from what’s relevant with dietpi, I will attach the text I copied from my SSH session when attempting to run MagicMirror with the command listed on the website. The intended outcome is for the program to display on the local monitor, but it doesn’t. However, not only doesn’t the program display, but the entire video output on the monitor goes blank about a minute after the banner appears on TTY1. This issue started happening after installing LXDE and selecting the autostart for login and LightDM. Basically, the HDMI output works fine while it’s bootloading, and it stays displaying the postboot banner with the line that says “Please hit return to login”. I don’t own a USB OTG cable, so I have no way of checking if it would even enter the desktop if I pressed it. But after ~1 minute, the entire screen goes blank (HDMI keeps outputting fine, but displays a fully). However, the Pi is still on and works fine via SSH and VNC. Infact, I was able to get MagicMirror working perfectly by installing TigerVNC and setting x0vncserver to display 0, that way I was able to access the desktop (albeit the screen on the local monitor stayed blank). I hope that the details are understandable, this is just a very confusing thing to explain - as I don’t understand what’s happening lol.

I will also attach the journalctl log. The exact moment where the screen went black was when “systemd[1]: dev-dri-card0.device: Job dev-dri-card0.device/start timed out.” appeared.

To recreate:

  • Download the Raspberry Pi 2 PCB v1.1 Build of Diet Pi
  • Flash the ISO onto a Sandisk Ultra SD card with Raspberry Pi Imager
  • Insert the SD card into a Pi Zero 2W and wait through the setup process
  • When prompted, install LXDE and Chromium from the Dietpi software menu.
  • Enter autostart menu and enable Autologin and LightDM Login Mask
  • Overclock the CPU to 1.3Ghz as shown on the guide
  • Reboot the Pi and run the Magic Mirror curl install script (No PM2 for now)
  • Attempt to run Magic Mirror with the “npm start” command
    -Additionally, install TigerVNC and access the desktop remotely.

Required Information

  • DietPi version |
    G_DIETPI_VERSION_CORE=9
    G_DIETPI_VERSION_SUB=9
    G_DIETPI_VERSION_RC=0
    G_GITBRANCH=‘master’
    G_GITOWNER=‘MichaIng’
    G_LIVE_PATCH_STATUS[0]=‘applied’
    G_LIVE_PATCH_STATUS[1]=‘applied’
    G_LIVE_PATCH_STATUS[2]=‘not applicable’
    G_LIVE_PATCH_STATUS[3]=‘not applicable’

  • Distro version | bookworm 0

  • Kernel version | Linux MagicMirror 6.1.21-v7+ #1642 SMP Mon Apr 3 17:20:52 BST 2023 armv7l GNU/Linux

  • Architecture | armhf (32 bit OS on an Armv8 SBC)

  • SBC model | Raspberry Pi Zero 2W

  • SD card used | Sandisk Ultra 32 GB

(The blank screen appears with just LXDE installed, it is not related to MagicMirror afaik. No task seems to trigger it, check journalctl)

magicmirrorlog.txt (5.1 KB)
journalctl.txt (57.2 KB)

2

For testing you could test various display settings usind dietpi-config

2 Likes
3

Wow, simply changing the resolution in display settings fixed it. I feel so dumb lol. By the way, is there a way to remove/bypass the “Please hit return to login” screen? It really adds to the boot time. Is it a LightDM/Xorg related config? Thanks!

4

This is the local console login. This has nothing to do with xorg.

5

Ah, my bad. Still new to this. Just wondering if it’s possible either remove that prompt on the local console, or shorten the time. I don’t think disabling getty would work, but I can’t find a config regarding it.

6

I don’t think it will be possible to remove, you can just login automatically

7

I just realized that I had read another thread regarding this issue, but ignored it. This thread is about a 1.5 minute delay on startup, caused exactly by the same reason as mine: dev-dri-card0.device and dev-dri-renderD128.device. What I had done by “changing to 720p in dietpi-config” was me changing from VC4-KMS to what (I assume) is the framebuffer. The issue with those 2 devices persisted, but it didn’t seem to affect Xserver or whatever. When I followed your solution by masking those 2 devices, the postboot prompt on the local display was completely gone and it booted in a few seconds! But the problem is that I think those devices are used for 3D acceleration, which I may or may not need.

I also wanna add that using the VC4-FKMS option does display fine, but has the same issue with those 2 devices (thus, long boot time aswell). I’m kinda confused on was said on that thread about LightDM, should I change/downgrade it? I’ll probably keep those devices disabled for now, so that atleast it boots fast lol.

8

Yes downgrading LightDM was a workaround

9

I ended up running the commands that Michalng posted on that thread. Those being,

echo -e 'Package: src:lightdm\nPin: origin archive.raspberrypi.com\nPin-Priority: -1' > /etc/apt/preferences.d/dietpi-lightdm
apt update
apt install --reinstall --allow-downgrades lightdm=1.26.0-8

The result was interesting, as after running it, the error regarding the 2 devices was completely gone without having to mask them. However, this is only the case when using Framebuffer/Legacy or FKMS in dietpi-config. As using KMS still results in a blank screen postboot (SSH and remote Magic Mirror still work fine). KMS would probably be better, but I’ll likely stick with FKMS for now.

Journalctl logs from KMS and FKMS attempts. I’m happy to provide more details.
kms.txt (52.5 KB)
fkms.txt (53.5 KB)
(sorry for asking so many questions, i’m really new to this)

10

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.