AGX Xavier - two HDMIs not working at the same time

Hi Nvidia Team

We face an issue with two HDMI Ports. If we enable each separately HDMI0 and HDMI2, they both work. If we enable both together, only one works (HDMI2). It seems something similar to this topic:

However, just turning the regulator always on does not solve it for us.
Can you help us?
Thank you.

Kind regards

You need to provide the dmesg when error happened so that I can tell what is going on.

Honestly, please take this as a common sense when you file a topic. It is not possible for us to just tell what is going on with your brief comment.

Hi WayneWWW

Here are the dmesg and the Device Tree:

dmesg.txt (67.9 KB)
two_hdmi.dts (379.9 KB)

Could you probe if one of the vdd_hdmi_5v0 is not getting up when another one is in use?

Also, is hotplug case able to wake the monitor up if you remove the one that was in use?

For example,

Monitor A → working
Monitor B ->not work

→ Remove the HDMI cable of A and then hotplug the cable of B. Will B be able to power on?

Hi WayneWWW

When both displays enabled, the vdd_hdmi0_5v0 is not getting up. We control the HDMI regulator over the Pin C59 (I2S3_CLK). When HDMI2 is disabled, the vdd_hdmi0_5v0 is getting up to 5V.

By hotplugging, only the Monitor working before will work again.
Monitor A > working
Monitor B > not working

Remove cable A, hotplug B → B still not working, hotplug A → Monitor A working

We further noticed than when we disable sor2, that we get a white screen on the monitor connected to HDMI2.
Thank you for your support.

Hi WayneWWW

Finally we are able to use both HDMI ports at the same time. In the first try with the “regulator-always-on” parameter, we had an error and therefore the monitors were not working. Now we added this argument to both HDMI regulators and both monitors are working. However we think it should be possible to use both HDMIs without turning the regulators always on. Is there another solution to make it work?
Thank you.


Could you clarify whether this issue is due to the GPIO pin from jetson does not enable the regulator or not?

Yes, when both hdmi’s are active, the GPIO of the Jetson does not enable the Regulator of the HDMI0.

But when single case is in use, the GPIO of regulator on HDMI0 is working again?

Yes that is exactly what is happening:

just HDMI0 enabled → regulator turns on as expected
HDMI0 and HDMI2 enabled → GPIO of HDMI0 does not turn on 5V regulator


Sorry for late reply. I think you need to check the kernel driver and see why the regulator is not enabled.

The driver code should be dc_hdmi_hotplug_init function inside


Actually, since most of our board design is using always-on regulator, it has chance that this one was never in use.

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