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Hello, i got a tuxedo pulse so with a 4800h with vega 7 integrated. 

On openSuse leap 15.2 HDMI does not work.
On OpenSuse leap 15.3 HDMI works, excep one things: DPMS.

That is to said that when after an idle time, kde should lock the screen (that
work), and the external HDMI display should go to sleep. 

But, the display never go to sleep, it turn black during 2s (not in sleep mode,
just a black frame), then the lock screen goes back so display will never go to
sleep, it will display the lock screen all the time. 

I could reproduce the things manually with:
xset dpms force off/xset dpms force suspend. 
The external display never go to sleep. 

It works for the internal display, so it's related to HDMI. 

Reproducible: Always

Steps to Reproduce:
1.xset dpms force off/xset dpms force suspend or (let default idle lock screen
appear)

Actual Results:  
Display print black picture for 2s, and then the lockscreen or the desktop (if
you use xset on terminal) goes back again


Expected Results:  
External hdmi monitor should go to sleep with orange led. 

Problem appear on HDMI only (it's ok for the internal display if no external
display are plugged)

When the dpms does not work, i see this error on dmesg:
[20603.565532] [drm] Failed to add display topology, DTM TA is not initialized.
[20603.693852] [drm] Failed to add display topology, DTM TA is not initialized.
[20618.122533] [drm] Failed to add display topology, DTM TA is not initialized.
[20618.250046] [drm] Failed to add display topology, DTM TA is not initialized.
[20648.646822] [drm] Failed to add display topology, DTM TA is not initialized.
[20648.773445] [drm] Failed to add display topology, DTM TA is not initialized.
[20669.520258] [drm] Failed to add display topology, DTM TA is not initialized.
[20669.647097] [drm] Failed to add display topology, DTM TA is not initialized.
[20894.046219] [drm] Failed to add display topology, DTM TA is not initialized.
[20894.174706] [drm] Failed to add display topology, DTM TA is not initialized.