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The problem with your setup is that you're using TVs for multiple
displays. Like you said, TV's don't understand DPMS so it's
impossible to get them to power down on command. Most newer TVs do
understand CEC and it's possible to get a CEC injector (I believe
NVIDIA doesn't handle it in their cards) to send a signal for the TV
to power itself off/on when you want it to. The biggest problem is
that when TVs turn off, they stop,for the most part, reporting on
the cable that they are there, so from the point of view of your
system, you are unplugging and plugging in the TV's from the system,
probably in some random order, and the system has to quickly deal
with handing changing scenarios of one monitor configuration after
another as the TVs turn on... It's probably freaks out because it's
asked to setup a display on one TV.... no wait 2 TVs... Just
kidding 3 TVs... but it's still trying to handle the first one by
the time it's asked to handle the 3rd one. I have a feeling that
TV's also don't have the unique ID's that monitors have so it will
also struggle to automatically place them back in the correct order
once they are all up and running if you are using the same model TVs
for all your displays.<br>
<br>
I personally use a single 50" 4K display for my desktop and other
than having to turn it on and off by hand, it has worked flawlessly
for the past 5 or 6 years... but then again, I'm only using the one
TV for my display. Before that I used a 3 monitor setup, with
actual computer monitors and I didn't have any problems at all with
that. My brother had a system with I believe 16 computer monitors
and that worked very well as well, but again that were actual
monitors. <br>
<br>
I think I remember coming across a device that was a DPMS proxy that
might fix your problem. It basically sits between you computer and
display and fakes a monitor signal to your computer so that your TVs
don't appear to be disappearing and reappear to your computer
constantly.<br>
<br>
You could also hard code your display setup in your Xorg.conf so
that it would have no choice but to setup your display like you like
it, but that could make things difficult/stange for you at a later
date if you ever change your display setup.<br>
<br>
Or, you could always get real computer monitors, but that would be
very expensive which is probably why your using TVs in the first
place.<br>
<br>
Brian<br>
<br>
<div class="moz-cite-prefix">On 8/20/20 5:25 PM, Michael Butash via
PLUG-discuss wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CADWnDsuj8p+RPF4Wv57dLj4+a+eNN76oFcTvKaPCxzeyqiYg1g@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">
<div>I have had lots of issues with video and adapters the past
few years, mostly as I'm forced to use them. My nvidia 1070
in my desktop has 3x DP1.2 ports and 1 HDMI2.0. I have 3
displays, so I use the 3x DP1.2 ports, and run those through
adapters to HDMI2.0 on my Samsung TV's I use for monitors.
Non-stop chaos ensues during power-down and up every day,
something different, every linux desktop hates it. Often one
display or another will freak out, and I end up; having to
hard disconnect the adapter (ie, reboot it) to work again or
it'll come up stuck in 768x1024 (on a 48" tv...).</div>
<div><br>
</div>
<div>I found HDMI doesn't handle DPMS sort of power-off modes as
vga, dvi, dp, or most methods of displays to handle soft
power-off scenarios, ala just power down displays. When my
laptop powers them down, they remain on with no signal, which
seems to just confuse the video card and adapter that both
freak out. This seems to have a profound effect on displaya
and video cards that don't realize most displays are now
hdmi...<br>
</div>
<div><br>
</div>
<div>Graphic subsystems are a basketcase these days under linux,
mostly because of these damn adapters, <a
href="https://www.youtube.com/watch?v=-XSC_UG5_kU"
moz-do-not-send="true">dongles</a>, and vendor wars. Intel,
that wants to sell all the things, including the most useless
gpu on the earth, injects themselves into everything, and
always cause me issues as I can't convince the os to use the
(real) nvidia gpu. Probably the same sort of issue if an
intel gpu is around with AMD. Last I used an AMD GPU some 4-5
years ago, it was an issue. Nvidia Prime via Intel is still
sketchy af.<br>
</div>
<div><br>
</div>
<div>Even on a dedicated nvidia gpu in a server-ish xeon system,
with DP-to-whatever adapters I had nothing but issues. My
latest iteration is my laptop (xps 9560) and a
thunderbolt3/usb-c dock with 2x 4k/60hz outputs via one-piece
DP-to-HDMI cables. I still have quirks, but I've learned to
work around, and now somewhat understand really odd hardware
behaviour enough to reproduce it. Occasionally I still need
to disconnect a display at the DP-to-HDMI cable I use now,
which is again oddly random.<br>
</div>
<div><br>
</div>
<div>I don't like the adapters, but my 48" TV's I use for
displays don't often come with DP ports native, and using HDMI
comes with power management oddities. A lot depends on your
cabling and even display these days.</div>
<div><br>
</div>
<div>-mb</div>
<div><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Aug 19, 2020 at 1:05
PM Seabass via PLUG-discuss <<a
href="mailto:plug-discuss@lists.phxlinux.org"
moz-do-not-send="true">plug-discuss@lists.phxlinux.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>No, on the desired monitor, it still black screens.</div>
<div><br>
</div>
<div>Works just fine (Even without that parameter) on
something that has a direct HDMI cable, though. (TV)</div>
<div><br>
</div>
<div><span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">> Message:
6</span><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
<span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">>Date:
Tue, 18 Aug 2020 16:23:47 -0700</span><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
<span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">> From:
Aaron Jones <</span><a
href="mailto:retro64xyz@gmail.com" dir="ltr"
style="font-family:-apple-system,Helvetica,Arial,sans-serif"
target="_blank" moz-do-not-send="true">retro64xyz@gmail.com</a><span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">></span><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
<span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">> To: </span><a
href="mailto:plugaz@codezilla.xyz" dir="ltr"
style="font-family:-apple-system,Helvetica,Arial,sans-serif"
target="_blank" moz-do-not-send="true">plugaz@codezilla.xyz</a><span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">, Main PLUG
discussion list</span><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
<span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">> <</span><a
href="mailto:plug-discuss@lists.phxlinux.org" dir="ltr"
style="font-family:-apple-system,Helvetica,Arial,sans-serif"
target="_blank" moz-do-not-send="true">plug-discuss@lists.phxlinux.org</a><span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">></span><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
<span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">>Subject:
Re: KMS but AMDGPU And Black Screen</span><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
<span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">> Message-ID:
<</span><a
href="mailto:6B7D5942-0F2F-4DAE-A54A-19215718DCF2@gmail.com"
dir="ltr"
style="font-family:-apple-system,Helvetica,Arial,sans-serif"
target="_blank" moz-do-not-send="true">6B7D5942-0F2F-4DAE-A54A-19215718DCF2@gmail.com</a><span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">></span><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
<span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">> Content-Type:
text/plain; charset="utf-8"</span><br>
</div>
<div>><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
> <a
href="https://bugzilla.redhat.com/show_bug.cgi?id=1594488"
dir="ltr"
style="font-family:-apple-system,Helvetica,Arial,sans-serif"
target="_blank" moz-do-not-send="true">https://bugzilla.redhat.com/show_bug.cgi?id=1594488</a><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
<span
style="font-family:-apple-system,Helvetica,Arial,sans-serif">>
Set amdgpu.dc=0 in bios and it will work but without hdmi
sound.</span><br
style="font-family:-apple-system,Helvetica,Arial,sans-serif">
</div>
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