Created attachment 132142 [details]
Description of problem:
We are trying to solve an issue in which displays fail to wake up when booting a Rhel 7.3 machine (Machine A) connected to a Display Port KVM while the KVM is pointing to Machine B. The unusual bit is that xorg logs in /var/log/Xorg.0.log indicate that everything comes up correctly, and a "ps -ef |grep X|xinit" shows that X and xinit are up and running. If we boot Machine A while the KVM is pointing to it, the displays come up with no issues.
We have KMS parameters set to force the output of the video (video=DP-1:2560x1600D and video=DP-2:2560x1600D) as well as options to load the EDID information. These parameters have worked in the past for us when we used DVI connections through KVMs, but DisplayPort is not showing the same results. Note that we have additional kernel options added for extra debug information (log_buf_len=8M nouveau.debug=disp=trace,i2c=trace,bios=trace)
Using Xrandr and Udev rules with a script allow us to turn off and then back on the displays automatically, allowing us a workaround, but it still does not solve the core issue of that nouveau is not waking up the monitors.
Please see the attached logs/config files and diagram below for more information.
|Machine A| |Machine B|
\ _________ /
|Monitor 2| |Monitor 1|
Created attachment 132143 [details]
Created attachment 132144 [details]
xorg.conf for nouveau driver
You appear to be using a 3.10 kernel. This was released in June 2013. Nouveau has been rewritten ~3 times by now. Can you try more recent software?
Better DP link training logic is one of the things that has had a lot of revisions to it.
Separately, you appear to want to use the card in Zaphod mode, but you haven't explicitly enabled it... no clue what happens when you do it that way.
Thanks for your response Ilia.
I'm slightly confused by your comment. Currently, we are using Redhat 7.3 with kernal version 3.10.0-514, which is the latest version available as shown here: https://access.redhat.com/articles/3078
Nouveau's website indicates that the latest linux kernal available is 4.11.6.
I'm confused by this discrepancy, but I believe I'm misunderstanding something. Could you clarify a bit more?
(In reply to dhruv.a.thakkar from comment #4)
> I'm slightly confused by your comment. Currently, we are using Redhat 7.3
> with kernal version 3.10.0-514, which is the latest version available as
> shown here: https://access.redhat.com/articles/3078
This isn't the RH support forum. This is upstream. http://www.kernel.org/ has the relevant info of what the current kernel releases are.
Kernel 3.10 was released in 2013. Then someone at RH has been cherry-picking "important" fixes for the past 4 years. The idea of such stable branches is "if it worked before, it'll keep working". However for you, it didn't work "before".
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