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USB-C to DP monitor not recognized

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kefNurd1
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Joined: 2022-01-21 16:26

USB-C to DP monitor not recognized

#1 Post by kefNurd1 »

I have a laptop that has two video outputs available, one HDMI and one Thunderbolt. One connected monitor, HDMI to HDMI, is working fine. The other monitor, Thunderbolt to DisplayPort, is not getting a signal. I believe there are no issues with the hardware or the cable since the Thunderbolt-DisplayPort monitor does get a signal and both external monitors work fine when I use Windows.

In the past I've had trouble connecting to external monitors using DisplayLink chips, but I don't think this laptop is using DisplayLink hardware. The HW probe is at https://linux-hardware.org/?probe=a2817e6e7e.

I would normally troubleshoot by tailing the syslog as I plug the monitor cable into the laptop and seeing what error messages come up. In this case, the only messages I get are:

Code: Select all

Jan 21 11:38:18 alkaid kernel: [20119.047917] ACPI BIOS Error (bug): Could not resolve symbol [\_GPE._L2B], AE_NOT_FOUND (20210730/psargs-330)
Jan 21 11:38:18 alkaid kernel: [20119.047923] ACPI Error: Aborting method \_SB.PC00.LPCB.H_EC._Q86 due to previous error (AE_NOT_FOUND) (20210730/psparse-529)
Using Google I haven't yet been able to confirm either that this is related to the problem or a red herring.

Does anyone know if there's some unsupported hardware that preventing the laptop from connecting to the monitor, or have any other ideas about how to continue troubleshooting?

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bw123
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Re: USB-C to DP monitor not recognized

#2 Post by bw123 »

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NorthEast
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Re: USB-C to DP monitor not recognized

#3 Post by NorthEast »

kefNurd1 provided code:

Code: Select all

.... ACPI BIOS Error ....
I had a look at the hardware in your link. I'm not familiar with your machine but just looking at the code you might consider booting up with the kernel parameter: acpi=off to check the difference.

kefNurd1
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Re: USB-C to DP monitor not recognized

#4 Post by kefNurd1 »

people will need basic system info to help on here
@bw123, as far as I know that's provided in the post. If there's something you think I should add specifically, please let me know, I'll try to provide it.
you might consider booting up with the kernel parameter: acpi=off
@NorthEast, strangely, it gets this point:

Code: Select all

[  0.854802 ] Freeing unused decrypted memory: 2036K
[  0.855006 ] Freeing unused kernel image (initmem) memory: 2652K
and then no further. Progress just freezes. ?

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NorthEast
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Re: USB-C to DP monitor not recognized

#5 Post by NorthEast »

kefNurd1 wrote:
I haven't yet been able to confirm either that this (ACPI error) is related to the problem or a red herring.
....
(with acpi=off)
Progress just freezes
Red herring sounds good. I've found ACPI often outputs errors that don't affect normal use, but sometimes do.

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