BSP7 - HDMI HDP disconnect does not disable HDMI Data and Clock

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Hello Dario,

Thank you for your detailed description and for referencing your previous investigation.

Your findings are consistent with known HDMI hotplug detect (HPD) handling regressions in BSP 7 for the i.MX 8M Plus platform. As you observed, the HPD disconnect does not properly disable HDMI Data and Clock when using BSP 7.x, even though it works as expected with BSP 6.8.2. This issue has also been documented in other community posts, such as “Weston and Chromium crashes on iMX8MP after HDMI connector little movements/vibrations on touch”.

Important context:

  • The i.MX 8 series modules use the Linux kernel’s DRM/KMS subsystem to manage HDMI output in both BSP 6 and BSP 7. Updates or regressions in this stack with BSP 7 may impact the actual hardware response to HPD events (reference).
  • Some issues could arise from changes or updates to the Weston compositor, the DRM subsystem, or related kernel drivers between BSP 6 and BSP 7.

Suggestions for further debugging:

  1. Collect boot and runtime kernel logs (dmesg) for both BSP 6.8.2 and BSP 7.x while performing the HDMI disconnect/reconnect event. This may reveal differences in how HPD events are handled.
  2. Compare the relevant kernel DRM/HDMI log outputs for handling HPD interrupts.
  3. Examine user-space components, such as Weston or the compositor in use, as sometimes higher-level display managers might handle the hotplug differently.
  4. If you have a custom device tree or overlays, verify that there are no differences regarding HDMI settings between BSP 6 and BSP 7.

Unfortunately, if the code changes referenced in the earlier solution are still present in the 6.6 kernel for BSP 7 and do not resolve the issue, this points to a potential regression or behavioral change in the HDMI kernel stack or associated user-space components.

For your reference, these resources summarize the handling and changes around HDMI and display outputs on the i.MX 8 series:

If capturing and comparing logs highlights driver differences, you may want to investigate BSP 7-specific overlays, kernel patches, or configuration changes related to DRM, HDMI, or display hotplug support.

Please let me know if you need additional information about HDMI or display handling for your specific module. I’ll be happy to assist further!

Best regards,
Toradex AI Assistant.