Revolution pi Display is not working

[Bhanu Kiran]

Hi,

I’m experiencing an issue with the Revolution Pi display. Although I’ve enabled the Graphical Desktop in the Boot to GUI option and rebooted the device multiple times, the display isn’t working correctly. The screen shows the boot logs but then continuously flickers between white and black after booting.

Here’s what I’ve done so far to diagnose the problem:

1. Checked the LightDM service status:
- It appears that the LightDM service is running, but there are errors related to retrieving the user list from `org.freedesktop.Accounts`, as shown in the log below:

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     sudo apt update && sudo apt upgrade -y
     systemctl status lightdm

Output:

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     ● lightdm.service - Light Display Manager
          Loaded: loaded (/lib/systemd/system/lightdm.service; enabled; vendor preset: enabled)
          Active: active (running) since Mon 2024-08-19 08:41:10 UTC; 2s ago
            Docs: man:lightdm(1)
        Main PID: 6214 (lightdm)
           Tasks: 5 (limit: 2049)
           CPU: 591ms
        CGroup: /system.slice/lightdm.service
                └─6214 [lightdm]
     
     Aug 19 08:41:10 RevPi110834 systemd[1]: Starting Light Display Manager...
     Aug 19 08:41:10 RevPi110834 systemd[1]: Started Light Display Manager.
     Aug 19 08:41:10 RevPi110834 lightdm[6214]: Error getting user list from org.freedesktop.Accounts: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The >
     Aug 19 08:41:11 RevPi110834 lightdm[6242]: Error getting user list from org.freedesktop.Accounts: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The >
     Aug 19 08:41:11 RevPi110834 lightdm[6242]: pam_unix(lightdm-greeter:session): session opened for user lightdm(uid=110) by (uid=0)
     Aug 19 08:41:12 RevPi110834 lightdm[6242]: pam_unix(lightdm-greeter:session): session closed for user lightdm

2. Investigated potential issues with the `accounts-daemon`:
- I checked the status and attempted to restart the `accounts-daemon` and LightDM services:

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     systemctl status accounts-daemon
     sudo apt-get install accountsservice
     sudo systemctl start accounts-daemon
     sudo systemctl restart lightdm
     cat /etc/lightdm/lightdm.conf

3. Checked the LightDM journal logs:
- The logs indicate that the LightDM service is repeatedly failing and restarting:

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     journalctl -u lightdm
     
     Aug 19 08:59:59 RevPi110834 systemd[1]: lightdm.service: Failed with result 'exit-code'.
     Aug 19 09:00:00 RevPi110834 systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 277.
     Aug 19 09:00:00 RevPi110834 systemd[1]: Stopped Light Display Manager.
     Aug 19 09:00:00 RevPi110834 systemd[1]: Starting Light Display Manager...
     Aug 19 09:00:00 RevPi110834 systemd[1]: Started Light Display Manager.
     Aug 19 09:00:00 RevPi110834 lightdm[17313]: pam_unix(lightdm-greeter:session): session opened for user lightdm(uid=110) by (uid=0)
     Aug 19 09:00:01 RevPi110834 lightdm[17313]: pam_unix(lightdm-greeter:session): session closed for user lightdm
     Aug 19 09:00:01 RevPi110834 systemd[1]: lightdm.service: Main process exited, code=exited, status=1/FAILURE
     Aug 19 09:00:01 RevPi110834 systemd[1]: lightdm.service: Failed with result 'exit-code'.
     Aug 19 09:00:02 RevPi110834 systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 278.
     Aug 19 09:00:02 RevPi110834 systemd[1]: Stopped Light Display Manager.
     Aug 19 09:00:02 RevPi110834 systemd[1]: Starting Light Display Manager...
     Aug 19 09:00:02 RevPi110834 systemd[1]: Started Light Display Manager.
     Aug 19 09:00:03 RevPi110834 lightdm[17364]: pam_unix(lightdm-greeter:session): session opened for user lightdm(uid=110) by (uid=0)
     Aug 19 09:00:04 RevPi110834 lightdm[17364]: pam_unix(lightdm-greeter:session): session closed for user lightdm
     Aug 19 09:00:04 RevPi110834 systemd[1]: lightdm.service: Main process exited, code=exited, status=1/FAILURE
     

It seems that the LightDM service is encountering an issue with starting properly, possibly due to problems with `accounts-daemon` or a misconfiguration in LightDM. I’d appreciate any guidance or suggestions on how to resolve this issue. If more information is needed, I’m happy to provide it.

Thank you for your help!

[u.biakoup]

Bhanu Kiran;

what kind of revolution Pi are you using (connect 4, Connect S, core, etc)?

Here are some steps you can try to resolve the problem:

1. Reinstall LightDM and AccountsService
Sometimes, reinstalling these packages can resolve configuration issues or missing dependencies.

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sudo apt-get purge lightdm accountsservice
sudo apt-get install lightdm accountsservice

After reinstalling, reboot your system:

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sudo reboot

2. Check for Misconfigurations in lightdm.conf
Ensure that the LightDM configuration file isn't misconfigured. You can inspect the file:

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sudo nano /etc/lightdm/lightdm.conf
Make sure the configuration settings are correct and match the display settings of your device. If you're unsure, you can reset it by moving the current configuration file and reinstalling LightDM to regenerate it:

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sudo mv /etc/lightdm/lightdm.conf /etc/lightdm/lightdm.conf.bak
sudo apt-get reinstall lightdm

3. Check Display Drivers
Display issues can sometimes be due to incorrect or missing display drivers. Ensure that the correct display driver for your hardware is installed. You can use:

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sudo apt-get install --reinstall raspberrypi-ui-mods xserver-xorg-video-fbdev
sudo reboot
This will reinstall the necessary UI components and framebuffer driver

s.

4. Check Xorg Logs
The issue might be related to X server or display settings. You can inspect the Xorg logs for errors:

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cat /var/log/Xorg.0.log | grep "(EE)"
Look for any errors related to display, graphics drivers, or configuration

.

5. Investigate accounts-daemon Issues
Since the logs indicate issues with accounts-daemon, ensure it’s running properly. If you haven't already:

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sudo systemctl status accounts-daemon
sudo systemctl restart accounts-daemon

If it’s not starting or showing errors, you may need to reinstall it:

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sudo apt-get purge accountsservice
sudo apt-get install accountsservice

6. Check Permissions
Sometimes, permission issues with /var/lib/lightdm/ or related directories can cause problems. You can reset the permissions with:

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sudo chown -R lightdm:lightdm /var/lib/lightdm/
sudo chown -R lightdm:lightdm /var/log/lightdm/
sudo chmod 755 /var/lib/lightdm

7. Test with a Different Display Manager
If LightDM continues to fail, you might want to try using a different display manager temporarily, such as LXDM or SLiM, to see if the issue persists:

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sudo apt-get install lxdm
sudo systemctl disable lightdm
sudo systemctl enable lxdm
sudo reboot
This will switch to LXDM as the display manager

.

8. Try Running startx Manually
Test whether the X server can start manually by running:

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startx
If startx works, the issue is likely specific to LightDM.

9. Update the System
If you haven't already, make sure your system is fully up-to-date:

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sudo apt update && sudo apt full-upgrade -y
sudo reboot

10. Check for Hardware Issues
If all software-related troubleshooting fails, consider checking the hardware connections, especially if the display is an external device. Make sure all connections are secure.

If none of these steps resolve the issue, the next step would be to provide more detailed logs from the X server and LightDM, which might give more insight into the root cause.