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U2515H, Ubuntu 18.04.2, DP Daisy Chain problem (resolved)


I have a problem with 2 Dell U2515H monitors in daisy chain configuration under Ubuntu 18.04.2 using DP.

My configuration works great under Windows 10. I modified cables connection, enable DP 1.2 on monitors, and it works under win10, so the problem is not there.

In Ubuntu, I'm able to see my two monitors in configuration software (Nvidia and in settings). But one is black. Not always the same. Sometimes, when I boot, it's the first monitor where I can see my windows, and the other is black. And in the next boot, it's the exact opposite.

When I use my laptop screen and the two monitors, I put in configuration the black monitor between my laptop screen and the monitor which works, and I have a gap when I come from the laptop screen to the screen which is on. So the system sees the black monitor as a monitor, but I have nothing on it.

I change the default configuration to use KDE, and it's the same. I also create a new user, to be sure I have not a wrong configuration in ~/.config.

Does someone have an idea about this problem?



PS: Asus GL502V, GTX1070, Kernel 4.18 Ubuntu, latest Nvidia 4.30


Edit: I finally find a workaround. You only have to launch this command: 
xset dpms force off

Source: https://ubuntuforums.org/showthread.php?t=2301503

It works, but it's crazy to have to do this each time.

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