[Bug 105887] [GLK] no signal after switch resolution from 1080p at 23.98

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=105887

--- Comment #64 from user.forums at gmail.com ---
> I have this issue on my NUC7PJYH (Gemini Lake Pentium J5005) with a
> completely stock Ubuntu 18.04 Server installation using a Samsung 22" 1080p
> TV (I'll come back with the exact model number). Here's what happens:
> 
> 1. When you boot the system, the boot screen ("Intel NUC") is shown, as it
> should be.
> 2. Ubuntu starts to boot up and you get to see the first lines of console
> print-outs.
> 3. However, as soon as the system loads i915 and switches mode the screen
> goes black. The TV reports HDMI signal lost.
> 4. There are two ways to recover: disconnect and reconnect the HDMI plug OR
> power off and then on the TV.

My experience is identical to the above. I also have a NUC7PJYH with HDMI1
plugged into a Sony STR-DH810, which is plugged into a Panasonic VIERA
TC-P54V10 plasma TV. I'm running Debian sid/unstable. This problem only happens
with the NUC. If I swap out the NUC with any of my other boxes, it's fine.

I can confirm that applying
https://github.com/herrnst/ubuntu-bionic-kernel/commit/3d664ae3c8831a51139efbb5298fc27a1bee4950
"i915/glk: effectively disable hdmi_12bps_possible()" does in fact solve the
problem for me. It's my understanding this is a workaround rather than a proper
fix. If I can supply logging, edid, or something that would be helpful towards
a proper fix, please let me know.

Considering this problem does seem to be wide-spread, thank you to everyone
contributing to get it resolved! I just got this NUC and was really
disappointed to find this kind of bug.

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