[Abandonded] HDMI Switch display detection fails

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Song
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[Abandonded] HDMI Switch display detection fails

Post by Song » Tue Sep 18, 2018 5:43 am

Hello everyone,

I got myself a HDMI switch hoping to eventually have several devices connect to one display and I can just cycle through them.
For now I wanted to connect two Linux Mint machines but neither was able to properly detect or use the display on the other end of the switch.
Here's the setup:

Display: Benq GL2460 1080p
MachineA: Computer with Linux Mint 17.3 and a GTX 970
MachineB: Laptop with Linux Mint 18.3 and a GTX 1050m
Both have the latest proprietary nvidia drivers installed available to each system.

By default MachineA detects the display as unknown but doesn't get me full 1080p resolution. After some testing, it was able to properly detect the display when I connected the machine to a port on the hdmi switch MachineA hadn't used before. However, once restarting, changing to a terminal wih Ctrl+Alt+FX or the hdmi switch doing its thing, the detection was lost again and the default behaviour applies.

By default MachineB won't detect the display at all. After some testing, the same as with MachineA happened. It would detect the display on a new port of the switch but once any changes happened it would revert to the default behaviour.

Now, since both were once able to detect the display correctly at some point I'm assuming it's an issue with the auto detection being thrown off by the hdmi switch constantly auto switching on any change from its input ports?
Currently I'm hoping there is a way to have some configuration on both systems that, when they are connected to this specific switch, the display auto detection is turned off and they just assume there is that specific display on the other end?
Would be happy with any other solution though.

What information do you guys need to figure this out?

Thanks in advance!
Last edited by Song on Thu Sep 20, 2018 7:40 am, edited 1 time in total.

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Song
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Re: HDMI Switch display detection fails

Post by Song » Thu Sep 20, 2018 7:40 am

If anyones interested:
I did some more research and came upon the EDID stuff (display sending information about itself to the system). Apparently the hdmi switch sends corrupted edid information (at least in comparison to "proper" info from my display it seems corrupted). Although there are ways to force specific such EDID information through a kernel parameter (drm_kms_helper.edid_firmware) it didn't properly work in the short test I did nor would it be a solution applicable to both of my systems (as my laptop is reguarly connected to two entirely different displays).

Also it's really hard to boot a system when you haven't got any proper display output until login screen...

Anyway, I'll be returning the hdmi switch and looking for another one, preferably one that doesn't do that awful auto switching or maybe has specific support for Linux systems.

Cheers!
Last edited by Song on Thu Sep 20, 2018 8:03 am, edited 1 time in total.

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Moem
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Re: [Abandonded] HDMI Switch display detection fails

Post by Moem » Thu Sep 20, 2018 7:52 am

Thanks for posting that information. Even though you did not get it to work, knowing that (and why) may very well save someone else a lot of time!
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If your issue is solved, kindly indicate that by editing the first post in the topic, and adding [SOLVED] to the title. Thanks!

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