Black screen after booting sometimes in the Apalis imx8 board

Technical Support
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Hi, I’m the Toradex AI Assistant.

I might make mistakes or occasionally get you wrong. Our support team will step in if needed.

Based on your description, this intermittent black screen issue on your Apalis iMX8QM with Ixora carrier board appears to be related to a known HDMI initialization problem that can occur with certain displays and HDMI configurations.

Troubleshooting Steps

1. Verify HDMI Configuration

The Apalis iMX8 supports HDMI output natively (1). Ensure you’re using the correct device tree overlay for HDMI:

For Apalis iMX8 QuadMax, you should use the apalis-imx8_hdmi_overlay.dtbo overlay (1).

2. Check Weston Container Configuration

Since you’re running TorizonCore 6.2.0, there’s a known issue with Weston and HDMI displays that can cause intermittent black screens (2). Try running the Weston container with the atomic mode disabled:

docker container run -d --name=weston --net=host \
    --cap-add CAP_SYS_TTY_CONFIG \
    -v /dev:/dev -v /tmp:/tmp -v /run/udev/:/run/udev/ \
    --device-cgroup-rule="c 4:* rmw" --device-cgroup-rule="c 253:* rmw" \
    --device-cgroup-rule="c 13:* rmw" --device-cgroup-rule="c 226:* rmw" \
    --device-cgroup-rule="c 10:223 rmw" --device-cgroup-rule="c 199:0 rmw" \
    -e WESTON_DISABLE_ATOMIC=1 torizon/weston-imx8:4 \
    --developer

(2)

3. HDMI Hot Plug Detection

The Apalis iMX8 includes HDMI Hot Plug Detect (HPD) functionality (3). The intermittent black screen could be related to HPD signal issues. The HPD signal is available on pin 232 (HDMI1_HPD) (3).

4. Display Resolution and Timing

Ensure your 8-inch LCD (1024x768) is properly supported. The default HDMI overlay provides 1920x1080 resolution (1). You may need to create a custom device tree overlay with the correct timing parameters for your specific display.

5. Power Management

Since this occurs in automotive applications, consider that power fluctuations during startup might affect HDMI initialization. The issue happening in ~10% of boots suggests a timing-related problem during the display subsystem initialization.

Recommended Solution

  1. Update to newer TorizonCore version: Consider upgrading to TorizonCore 6.5+ or Torizon OS 7.x, which have improved HDMI stability (2)

  2. Implement the Weston workaround: Use the WESTON_DISABLE_ATOMIC=1 environment variable as shown above (2)

  3. Create a systemd service: Set up automatic container restart with the corrected Weston configuration to ensure consistent behavior on boot (2)

  4. Monitor HDMI status: You can add monitoring scripts to detect when HDMI output fails and automatically restart the display subsystem

The workaround with WESTON_DISABLE_ATOMIC=1 has been confirmed to resolve similar intermittent HDMI black screen issues on Torizon OS (2).

Best regards, Toradex AI Assistant.

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