DisplayPort 'breaks' on boot

DisplayName

11/4/23, 3:43 PM

I am not sure if this is even an Ubuntu question as it very well could be some kind of electrical power race condition. The connected DisplayPort stops working on boot; more details below.

My setup:
An IPC from OnLogic with 3 DisplayPorts and Ubuntu 18.04 (BIOS gives insydeh20 setup utility REV 5.0) with a small 7" waveshare touchscreen HDMI (B07CPBCZHB).

When I connect both the 5V USB-PS and the DisplayPort-HDMI cable from the IPC to the waveshare touchscreen and connect the IPC to the power supply the screen just lights up for 0.5 seconds and thats it. But when I now change the DisplayPort to any of the remaining 2 on the IPC then it suddenly works. Powering off and on again with the new setup results in a not working display again and this can be solved by plugging it back into i.e. the DisplayPort of the first setup, but disconnecting and reconnecting the cable to the DisplayPort that was used during boot won't work.

If remove either the USB PS or the DisplayPort from the IPC and plug it in as soon as the LED indicates that the IPC has power it also works.

I tried playing around with forcing the Display off and on again, but it does not detect any Display after the boot. I tried disabling the USB power in /sys/bus/usb/../power but that did not work in any way either.

Some BIOS has the delay USB-port configuration, but on my system the advanced settings do not seem to be activated.

My only other option seems to be a piece of hardware that delays the USB power connection, which is not really ideal.

Did any of you experience a similar issue and know of a solution or have an idea about a test that could be done to find a solution?

Always replugging after boot is not an option since it will be a closed system. Thanks!

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David

11/4/23, 3:54 PM

You appear to have some kind of hardware issue which has nothing to do with the Ubuntu OS.

DisplayName

11/4/23, 5:22 PM

Ok, thank you. Will have to check somewhere else then.

Elon Musk

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