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Redmattski

Member

Registered: 2016-10-26

Posts: 18

[Solved] HDMI detected as DisplayPort

Hi

I have an Asus Z170-deluxe motherboard with Intel 530 HD integrated graphics.  There are two graphics ports, 1x HDMI and 1x DP.  I have a HDMI cable running from my computer to my smart TV (Samsung QE75Q8DN).

Issues/symptoms:

- the TV displays no signal through the uefi part of the boot
- when the computer has booted (xfce4 with lightdm), the display is detected as DP-2 rather than HDMI.
- the maximum resolution of the DP-2 display is 1024x768, which cannot be extended with xrandr
- If the TV is switched off then on again, the only way of seeing the display is by restarting the computer
- no sound is passed over the HDMI cable to the TV (pulseaudio and pulseaudio-alsa installed)

Note: with my old LG 42" dumb TV, I can get access to the UEFI menu, achieve HD desktop resolution and hear sound over the HDMI cable.

Attempted Remediation

-I have tried running with and without the xf86-video-intel driver (defaulting to modesetting)
-Enabling early start KMS
-enabling guc=2 both in grub and via modprobe (guc=3 also tried)
-Different HDMI cables

Results

When I initially loaded guc=2, the TV displayed the UEFI menu and allowed a resolution of 4k on the desktop but no sound via HDMI.  However,  whilst trying to rectify the sound issue (by changing the source in pavucontrol) and the screen immediately switched off.  Since then, I have not been able to replicate that setup.

All the issues seem to be related to a single root cause.  Could anyone suggest how I can proceed forwards on this issue?

Thank you in anticipation

Last edited by Redmattski (2019-02-08 23:37:43)

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 20,715

Re: [Solved] HDMI detected as DisplayPort

This is a function of the television?  Does the 'dumb' TV still work as expected?

How long is your HDMI cable? Is it a high quality cable?

Is it possible that this new TV is defective by design as refuses to go to a high resolution state because of a lack of HDCP?  [Note that this is pure speculation in the form of brain storming... I have no evidence this is may be the problem]

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seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 78,686

Re: [Solved] HDMI detected as DisplayPort

You're gonna need a "HDMI Premium High Speed™" cable (I'm not making this up, the marketing BS is the official version) and HDMI v2.0 (yes, there's also a completely unrelated number version system…) to run 4k@60Hz.
Afaics the IGP only provides HDMI v1.4 (pray that it's 1.4b) and your Tv does not seem to have a DisplayPort input (because hey, why bother if you can confuse consumers with hdmi - grrr)

Ie. you *must* be able to run the Tv either at a lower resolution (2560 × 1600p @ 60 Hz) or 4k at30Hz - if the Tv doesn't accept those signals, there's no way you can use it this way (XGA is in the VESA spec, all outputs have to support it to get a nice VESA logo - everything else and above is sheer luck)
If you want to add resolutions, make sure they fall in that range. You can also try reduced blanking.

The DisplayPort output should be 1.2, so it'll support 4k @60Hz just fine. In doubt get a capable adapter DP => HDMI 2.0 and the most expensive hdmi cable you can find (just kidding, the price is unfortunately no quality indicator. No - I don't like hdmi)

PS: seems like the Tv is €3000, but DisplayPort wasn't in the cards?

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Redmattski

Member

Registered: 2016-10-26

Posts: 18

Re: [Solved] HDMI detected as DisplayPort

Thanks for the response

This is a function of the television?  Does the 'dumb' TV still work as expected?

The dumb TV (a 10 year old LG 42LH3010) still works correctly with the computer (with a maximum resolution of 1080p)

How long is your HDMI cable? Is it a high quality cable?

The HDMI cables I have tried are 1m, 2m and 3m.  The 2m cable was a high quality cable.

Is it possible that this new TV is defective by design as refuses to go to a high resolution state because of a lack of HDCP?  [Note that this is pure speculation in the form of brain storming... I have no evidence this is may be the problem]

As mentioned earlier, for a brief period, I managed to achieve 4k@24Hz with the smart TV and computer.  I assume the issue is software based but I do not understand why a setting on Linux would impact the UEFI.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 78,686

Re: [Solved] HDMI detected as DisplayPort

If it was a warm boot, something you did to the IGP might have carried over to its state during the UEFI init.
What happens if you try to add a 24Hz 4k resolution to xrandr for that output? (Exact command I/O)

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Redmattski

Member

Registered: 2016-10-26

Posts: 18

Re: [Solved] HDMI detected as DisplayPort

Thank you seth & ewaller.

It seems the solution is hardware based related to my cable, which I assume is damaged in some way.  This evening the output switched back to a 4K output briefly, this time with sound however after 5 mins the signal was lost again.

I will mark this thread solved and get a new "HDMI Premium High Speed™" cable.

Thanks again