Setting resolution to 4K kills nouveau ... but how do I recover?

[Richard W.M. Jones]

I've got a new machine with an nVidia card and an external 4K display.
For whatever reason selecting 4K in the graphical display resolution
tool causes the Nouveau driver to crash.  After this I can no longer
log in because even after a reboot it tries to select 4K again.

How can I (from ssh) change the display resolution back to something
lower?

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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[Tom Horsley]

On Tue, 3 Sep 2019 17:46:53 +0100
Richard W.M. Jones wrote:

>  How can I (from ssh) change the display resolution back to something
>  lower? 
If it stores it on a per-user basis, perhaps creating a new user
via ssh would allow you to login? 

This could be this bug:

https://bugzilla.redhat.com/show_bug.cgi?id=1648608

[Richard W.M. Jones]

On Tue, Sep 03, 2019 at 01:24:02PM -0400, Tom Horsley wrote:
>  On Tue, 3 Sep 2019 17:46:53 +0100
>  Richard W.M. Jones wrote:
>  
>  > How can I (from ssh) change the display resolution back to something
>  > lower?
>  
>  If it stores it on a per-user basis, perhaps creating a new user
>  via ssh would allow you to login?  
That's a good idea - wish I'd thought of it before :-/

It turns out that you can remove this file:

.config/xfce4/xfconf/xfce-perchannel-xml/displays.xml

which resets everything.  I guess that's XFCE only of course.

>  This could be this bug:
>  
>  https://bugzilla.redhat.com/show_bug.cgi?id=1648608 
The messages from nouveau were these, but they don't look very similar
(to anything online in fact):

[  296.106830] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119007
[  296.190651] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000
[  296.194547] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000
[  296.198445] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000
[  296.202331] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000
[  296.206210] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000
[  296.216671] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000
[  296.230534] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000
[  296.237774] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000
[  296.258270] nouveau 0000:09:00.0: i2c: aux 0005: timeout 01119000

There were no additional messages in journalctl either.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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