Yep, I've looked at DP/MST mode for a while now, but either linux support
was rather limited, or gpu support was limited when I needed it prior.
Plus your link says MST is good for 24Gbps throughput, which is about
enough for only 1 4k 4:4:4 signal (18Gbps), even 4k/30 comes in at 10.2Gbps
so only 2 (theoretically might work, I can live with 30hz).
The active DP might be worth looking at again, that one was only 30hz
though, which tends to be some of the problem, I couldn't find any full
4:4:4 that weren't really expensive. Bit hard to get full signal out of
some of these Chinese crap gadgets.
I did look closer at the cheap EDID adapters Brian sent, and looking at
like models a few specifically state "not compatible with DP to HDMI
adapters", which is exactly my scenario. I learned trying to use
dp-to-hdmi adapters with "active" thin hdmi cables did not work, and no
other active translation seems supported with more than one, including
these sadly.
I think you're both probably right, I'd need to use something like a set of
active devices across them, if they even make a DP in and full 4:4:4 HDMI
out adapter as an active, intelligent translator device. It's an old pain,
but talking about it again has me interested enough I'll shop around and
see what I can find that can spit out a full 4k signal these days.
Thanks for the good tips to consider!
-mb
On Mon, Aug 24, 2020 at 8:57 AM Stephen Partington via PLUG-discuss <
plug-discuss@lists.phxlinux.org> wrote:
> Did you ever try/consider something like this. Displayport to multiple
> HDMI out?
>
>
> https://www.amazon.com/StarTech-com-DisplayPort-HDMI-Multi-Monitor-Splitter/dp/B015J8Q6ZK (many
> options here. not al lare create even remotely equal...)
>
> And the active DP->HDMI costs have come way down. (This may be what you
> need for it all to play nice)
> https://www.amazon.com/dp/B07D2HSH4D/
>
>
> On Mon, Aug 24, 2020 at 7:23 AM Michael Butash via PLUG-discuss <
> plug-discuss@lists.phxlinux.org> wrote:
>
>> <pulling some offline discussion back into this, I think relevant to
>> others cheap geeks wanting to use a big tv too>
>>
>> You're right, the ports on the dock are DP1.2, but the TV is HDMI2.0, so
>> using an all-in-1 DP-to-HDMI cable, presumably the dongle chip built into
>> it, but hopefully better being "built in" together than a separate
>> DP-to-HDMI dongle+cable.
>>
>> Even using matched dongles and cables had recurring issues, similar to
>> Linus Tech Tips on youtube using an 8k TV, that required literally 4x HDMI
>> connections to use the 8k setup, and none would sync with each other.
>> Using a combo DP-to-HDMI cable resolved this (provided by the TV vendor of
>> course), but dongle+cable was a no-go.
>>
>> I've done a fair amount of diag watching the display churn during
>> power-down, no signal, etc and per xrandr it's typically showing the
>> correct display modes, and presence of the display (while in power down,
>> but os seems to know it's not active to use it). KDE, which when it isn't
>> infuriating me, tends to be what I use, and it just always does a horrible
>> job of shifting windows, display settings, refresh/resolution, etc during
>> these transitions of all/some displays at once. It's not only KDE though,
>> Cinnamon, Mate do it too, seems a systemic issue outside the DE. Plus it
>> happens with either Intel or Nvidia, so that leaves me staring at the
>> kernel, or xorg itself being quirky.
>>
>> I think you're right with a static edid and a device to do it, I've
>> considered this in the past with some of the magic video adapters that do
>> this for various odd devices, but were expensive for adapters when I need
>> 2-3 of them (they were over $100ea last I looked). These little single
>> shot static units might work if I can find one for HDMI-to-HDMI.
>>
>> However my fear is the problem is more with the DP to HDMI chip that is
>> translating, either in a dongle or built into a cable, which I think is
>> where things get flaky (since I have to still "reboot" them occasionally
>> with a cable pull. If that is glitching, I don't think a static edid
>> adapter would even help at the hdmi end as I think the issue is more at the
>> DP and adapter side.
>>
>> Native HDMi ports would probably work, but no one makes a multi-HDMI card
>> or dock I've found, at least not for 4k/60 x2 or 3 displays. The docks I
>> did find were typically DisplayLink chip-based docks, which make crappy
>> usb-to-video chips with dubious linux driver support, particularly anything
>> not already 3-4 years old. DisplayLink has always been Linux-unfriendly,
>> and just not something I'll bother with.
>>
>> Nothing is ever perfect....
>>
>> -mb
>>
>>
>> On Mon, Aug 24, 2020 at 4:48 AM Brian Cluff <brian@snaptek.com> wrote:
>>
>>> If all your connections all end up plugging into the HDMI port of the
>>> TV. You should be able to just plug the EDID device directly into the TV
>>> and your HDMI cable into it and it should solve all your problems... Unless
>>> I've missunderstood and you have found some TVs with displayport
>>> connections on them.
>>>
>>> Brian
>>>
>>> On 8/23/20 7:00 PM, Michael Butash wrote:
>>>
>>> That looks pretty cool, but my dock is 1x TB3 in, and 2x DP1.2 out on
>>> there, so really the problem is adapting DP1.2 to HDMI there to 2 of the
>>> displays. My third display mostly sees playstation activities these days
>>> until I screw around with my failed desktop, but still use 2x TV's with my
>>> built-in 4k laptop display as 3rd.
>>>
>>> I used to use a separate hdmi cable and a DP-to-HDMI adapter, but
>>> randomly saw someone else having issues with them (particularly with 8k
>>> displays muxing across them), then got an integrated DP-to-HDMI cable I had
>>> better hope for (could not find his exact brand). It's a bit better, but
>>> still occasionally requires reseating. I suspect this is a bug in the
>>> hardware/firmware on the adapter soc, but who knows.
>>>
>>> Maybe what I need is one of those adapters for more hdmi-to-hdmi at the
>>> tv end, or DP-to-DP for the same at the dock end. I'll look around see if
>>> something like what you sent me.
>>>
>>> Appreciate you look around on this for me, I have really odd issues no
>>> one ever else much seems to. Perhaps self-inflicted gunshot wounds, but I
>>> like to think I'm pushing boundaries. ;)
>>>
>>> -mb
>>>
>>>
>>> On Sat, Aug 22, 2020 at 10:41 AM Brian Cluff <brian@snaptek.com> wrote:
>>>
>>>> I think I've found the solution to your display problems, you just need
>>>> to buy a 3 pack of these (relatively inexpensive):
>>>>
>>>> https://www.amazon.com/FUERAN-stabilizer-Thunderbolt-fit-Headless-4k-3840x2160/dp/B07ZYLGDK3
>>>>
>>>> Just read the reviews. It sounds like it solves your exact problem.
>>>> The reviews also say that it can be used with a displayport to HDMI adapter
>>>> unlike what the product description says. The product has a lot of
>>>> chinglish in it so I think what they mean is that it's not a displayport to
>>>> hdmi adapter.
>>>> https://www.amazon.com/product-reviews/B07ZYLGDK3/ref=acr_dp_hist_5
>>>>
>>>> It appears you need to purchase the correct device for the resolution
>>>> you want to run and then once plugged in it just tells the system that
>>>> there is a display connect all the time, even if it's turned off or there
>>>> isn't one plugged in at all. This is the device that I was mistakenly
>>>> calling a DPMS proxy in my previous message. I had forgotten that it's
>>>> actually an EDID proxy, and they are a lot cheaper than when I was trying
>>>> to solve my similar problems in the past.
>>>>
>>>> I hope this helps...
>>>>
>>>> Brian Cluff
>>>>
>>>>
>>>>
>>>> On 8/22/20 8:30 AM, Michael Butash wrote:
>>>>
>>>> All valid points and correct Brian, cost vs. function. ~3yr ago when I
>>>> bought these displays, I was moving from 6x 24" ancient dell lcd's, and got
>>>> a "good" deal on these for about $650ea, curved samsung 48" 4k/60
>>>> displays. Couldn't get close to that with a real large monitor, let alone
>>>> curved (great for my desk) and in fact really couldn't find any period
>>>> except some off-brand chinese ones I expect to last no more than a year.
>>>>
>>>> I'd purchased a CEC injector to play with, but kind of a pain to run
>>>> and sync 3 of them at once, plus ~$50ea. Was going to try a rs232 adapter
>>>> on a quad serial adapter, but eventually realized I can live with shutting
>>>> off the displays manually via good old remote.
>>>>
>>>> The problem comes in doing so, you can't really catch and power-down
>>>> all at once, which causes video subsystem to start resizing from 3
>>>> displays, to 2, to 1, then none, which pretty much freaks out KDE and other
>>>> DE's. KDE has been notoriously horrible about multi-monitor support over
>>>> the years, window placement/size preservation, random resolution setting
>>>> resets, things like that. Now add in some dongles that randomly require a
>>>> physical disconnect to resume proper function randomly, every day,
>>>> sometimes multiple times a day if I have power management shutting down
>>>> displays, and it gets infuriating rather quickly. This was on my desktop
>>>> with a dedicated video card even!
>>>>
>>>> Now I'm using my laptop and the TB3 dock, which I find if I simply walk
>>>> up and yank the dock TB3 connector, so all external displays drop at once,
>>>> then power them down, they actually work fairly normally. I have to
>>>> disable power down of displays, but since the tv's won't shut off entirely
>>>> anyways, isn't that big a deal, other than the constant heat these generate
>>>> and my failing old AC in the house.
>>>>
>>>> I'm a bit more surprised HDMI still this day doesn't support DPMS-type
>>>> functions to some extent, even if "legacy" vs. only CEC. Likewise I'm
>>>> surprised companies like samsung don't just include a DP port on their TV's
>>>> too, as it's more common to see folks like yourself and I using TV's as
>>>> displays, as most tv's are better quality and price than any available
>>>> "computer monitor" unless you need/want 144mhz gaming refreshes (that your
>>>> eyeballs can't see anyways).
>>>>
>>>> I figure at some point a developer might buy a few of these tv's and
>>>> realize how asinine this all is to use to resolve it, but considering here
>>>> we are in 2020 and my first reports of some of this stuff began a decade or
>>>> more ago, perhaps not. KDE is still working on trying to fix window
>>>> placement a decade or two on, seeing this just today...
>>>> <https://www.phoronix.com/scan.php?page=news_item&px=KDE-Apps-Window-Pos>
>>>>
>>>> -mb
>>>>
>>>>
>>>> On Fri, Aug 21, 2020 at 10:16 PM Brian Cluff via PLUG-discuss <
>>>> plug-discuss@lists.phxlinux.org> wrote:
>>>>
>>>>> 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.
>>>>>
>>>>> 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.
>>>>>
>>>>> 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.
>>>>>
>>>>> 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.
>>>>>
>>>>> 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.
>>>>>
>>>>> Brian
>>>>>
>>>>> On 8/20/20 5:25 PM, Michael Butash via PLUG-discuss wrote:
>>>>>
>>>>> 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...).
>>>>>
>>>>> 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...
>>>>>
>>>>> Graphic subsystems are a basketcase these days under linux, mostly
>>>>> because of these damn adapters, dongles
>>>>> <https://www.youtube.com/watch?v=-XSC_UG5_kU>, 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.
>>>>>
>>>>> 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.
>>>>>
>>>>> 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.
>>>>>
>>>>> -mb
>>>>>
>>>>>
>>>>> On Wed, Aug 19, 2020 at 1:05 PM Seabass via PLUG-discuss <
>>>>> plug-discuss@lists.phxlinux.org> wrote:
>>>>>
>>>>>> No, on the desired monitor, it still black screens.
>>>>>>
>>>>>> Works just fine (Even without that parameter) on something that has a
>>>>>> direct HDMI cable, though. (TV)
>>>>>>
>>>>>> > Message: 6
>>>>>> >Date: Tue, 18 Aug 2020 16:23:47 -0700
>>>>>> > From: Aaron Jones <retro64xyz@gmail.com>
>>>>>> > To: plugaz@codezilla.xyz, Main PLUG discussion list
>>>>>> > <plug-discuss@lists.phxlinux.org>
>>>>>> >Subject: Re: KMS but AMDGPU And Black Screen
>>>>>> > Message-ID: <6B7D5942-0F2F-4DAE-A54A-19215718DCF2@gmail.com>
>>>>>> > Content-Type: text/plain; charset="utf-8"
>>>>>> >
>>>>>> > https://bugzilla.redhat.com/show_bug.cgi?id=1594488
>>>>>> >
>>>>>> > Set amdgpu.dc=0 in bios and it will work but without hdmi sound.
>>>>>> ---------------------------------------------------
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>>>>>> To subscribe, unsubscribe, or to change your mail settings:
>>>>>> https://lists.phxlinux.org/mailman/listinfo/plug-discuss
>>>>>
>>>>>
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>>>>>
>>>>>
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>>>>
>>>>
>>>>
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>
>
>
> --
> A mouse trap, placed on top of your alarm clock, will prevent you from
> rolling over and going back to sleep after you hit the snooze button.
>
> Stephen
>
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