imx8mp: HDMI display blank/black problems

[mailinglist1 at johanneskirchmair.de]

Hey, 
We had some problems with the hdmi on the imx8mp and wanted to leave, what we found out about it, somewhere for others to find it.

The problem was that our hdmi display sometimes stayed blank after hot plugging and sometimes at startup. On older kernel versions 6.6 we did not have the problem with the not mainlined hdmi patches. 
We tracked the commit down that introduced the problem for us. It was the following “driver core: Enable fw_devlink=rpm by default”  https://lore.kernel.org/lkml/20231113220948.80089-1-saravanak@google.com/
So we switched back to FW_DEVLINK_FLAGS_ON via kernel parameter. Don’t really understand what the problem with RPM is.

So, this information is just for reference. Maybe someone has an idea what is going on here. And how to fix the problem in a more proper way.

Best regards Johannes