Hi,
Having a bidirectional HDMI Edid emulator connected to the computer, when I put the computer in sleep mode from a desktop like KDE, Mate, Cinnamon or Xfce (except GNOME, which works fine) and the screen was in 4K resolution, when I wake up the computer the screen is completely black, it does not receive an HDMI signal, no matter how much I move the mouse or press the keys, the monitor does not react. I then have to press the Ctrl+Alt+F1 keys to switch sessions, and when I do so the monitor begins to receive the HDMI signal and everything starts to work fine.
On the other hand, this is independent of whether the graphics platform used is X11 or Wayland, exactly the same problem occurs in both.
The problem is also independent of whether when the computer wakes up it has established that it should automatically show the lock screen or not, in both cases the same thing happens, absolutely nothing is seen, the monitor is completely black because it does not receive an HDMI signal.
It is also independent of the kernel, I have tried 5.15, 5.16, 5.17 and the experimental 5.18, and the same problem occurs in all of them: in GNOME it works perfectly and in the other desktop environments it does not, the problem that I have mentioned occurs.
My processor is an AMD Ryzen 5 3550H and my GPU is an AMD Radeon Vega 8 Graphics, I am using the Picasso graphics driver (video-linux).
If you want to know what kind of product I’m talking about, please search for “EVanlak Hdmi Edid Emulator Passthrough 3rd Generrtion” in your favorite search engine (sorry, I can’t put links in this message).
The curious thing is the following:
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In GNOME it works perfectly, I have tried it several times and it works perfectly in 4K resolution (and even higher, I have even tried 4096x2160 which is the maximum resolution supported by the bidirectional HDMI Edid emulator and it works perfectly), when waking up the computer having the screen resolution at 4K or higher when put in sleep mode, it shows the unlock screen without problems. I don’t know what is special about this desktop environment, it is the only one that works, it does it perfectly, without problems.
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In the other desktop environments (KDE, Xfce, Mate, Cinnamon…) it works if the screen resolution before putting it in sleep mode is less than 4K, in this case when waking up the computer the lock screen is shown without problems. But if the resolution is set to 4K or higher, the problem I mentioned occurs.
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If, having the black screen after waking up the computer in one of these environments, I wait 5 minutes for the lock screen to be launched (obviously without having the lock option activated after waking up the computer), then when I move the mouse, works! The screen is activated and you can see the lock screen.
Of course, in the Windows operating system it works just as well as in GNOME, it works without any problem.
Can you think of any idea that explains why this problem may be happening, and above all, why it works perfectly in GNOME, what is special or different about this environment compared to the others so that it works perfectly in it? Does it manage the display or power management in a different way than other environments?
Regards.