[CM3/Raspbian] How to use HDMI output?


I have a Devterm with an XFCE4 desktop environment.

Using “vc4-fkms-v3d” option only shows the raspberry pi boot screen on the external monitor.

And the desktop works on the internal LCD monitor.

I can’t find the external one in this case.

On the other hand, only the external monitor works when using “legacy” driver.

The internal LCD monitor just blank screen.

Is it possible to use an external monitor with the KMS option?

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I have the same issue. When booting using the standard SD card the external HDMI monitor shows the boot messages, but sideways. It seems to be in portrait mode. After booting it shows the raspberry pi splash screen. The devterm itself shows the desktop as expected.

It is a pure software issue, both display works, you need to set Xorg to use both screen, which may be a bit tedious to do on Raspbian, not sure if xrandr is installed by default.

Haven’t been able to test HDMI yet as my cable is yet to be found.